Lost World Themed 6x12 Cargo Trailer Conversion

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JasKolp

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2,354
Idaho, USA
First Name
Jason
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Kolp
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12037

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KN4TLR
Hello! So I've mentioned/shown my trailer a few times in my ML build thread and figured I would create one for my trailer to show how I've built the trailer out.

There's a few reasons why I decided to go with a cargo trailer conversion versus something else.
  1. Cost was the main factor; most prebuilt RV's and other trailers start well over $10,000 for something half the size of the cargo trailer I went with. The cargo trailer I bought was about $5,500 brand new, which was probably a bit more expensive than what I could have gotten for a different cargo trailer, but there weren't many options in my area for brand new trailers.
  2. Weight was also a concern: while the ML320 is rated to tow 5,000lbs, I didn't want something heavy since I knew I would be taking the trailer on BLM and FS roads which would mean that I needed the trailer to be able to handle those roads as well.
  3. I didn't like a lot of the layouts that the prebuilt trailers had. I personally don't like the dinettes that the majority of the trailers/RV's have, and many of the floor plans weren't open enough for my liking. I also really liked the idea of having a rear ramp that could double as a porch, but the trailers that had those were large toy-haulers most of which were too heavy for my ML to tow even empty.
  4. Also part of the interior, but I didn't want a full size shower and toilet in the trailer. Personally I think a lot of the RV's on the market make the bathroom way too large in these smaller trailers. I don't see enough bathrooms that can be packed down like in a pop-up in trailers that are less than 20ft long. To date, I still don't even have a kitchen sink in the trailer, but I am planning on building a shower inside the trailer that uses a drain in the floor, the kitchen faucet, and a curtain that can be put away in order to maximize the space in the little trailer.
  5. I wanted a trailer vs. a van or standard RV because I had plans for the ML. I spent several years looking for the Mercedes in order to build it into a "The Lost World of Jurassic Park" overland capable replica. Since the ML was capable of going off road to places that I wanted to go, and had a good towing capacity, It made sense to get a trailer instead of getting rid of it in exchange for a van or RV to convert. I also liked the idea of making a base camp somewhere and then using the ML for exploring the area and going places that the trailer might not be able to follow. This seemed to work out great during fall 2021 and spring 2022 when I was between jobs.

I purchased the cargo trailer in March of 2020 during the initial Covid shutdowns in the US. The only reason why I was able to afford it was because of the federal boost to unemployment after I got laid off (and kicked out of employee housing and moved in with one of my friends who would help me with the trailer and ML build), and decided to buy a new trailer since all of the used ones in my area were damaged, rusted out, or just as expensive as a new one with obvious issues that would need to be fixed before continuing with the build.

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In April of 2020 my job took me back and I started working again, making about $9/hr still living with my friend. Most jobs in my area didn't pay very much, and due to the pandemic most businesses weren't interested in hiring for much more than $10-12/hr which meant I couldn't afford housing on my own. My friend let me stay at his place so we could work on the trailer together while I continued working as a park ranger getting experience there so I could eventually start seasonal jobs and use the trailer to move around the country more easily and start taking federal seasonal jobs (which even though most only last 6 months still paid better yearly than the state park ranger jobs I currently was working/looking at).

Anyway, so the first thing we did after getting the trailer was gutting the existing plywood walls and insulating the interior. We used 1 inch thick foam board insulation on the sidewalls, and 1.5 inch thick insulation on the ramp, ceiling, and eventually floor. The 1 inch boards have an R value of 5, and the 1.5 inch boards have an R value of 7.5. To date, the only sections that remain uninsulated are the side door, the floor near the nose and ramp, and the ceiling around the ramp lowering mechanism.

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Next we installed pine tongue-and-groove boards for the walls. This was probably the longest part of the project when I was living with my friend, as I wasn't making much money, and lumber prices were starting to go up so we had to work on it very slowly. When I was living with my friend I didn't have enough money to pre-wire the trailer for solar or hookups, so the plan was to add those systems later and hide them in the future cabinets and such instead of behind the walls like what is normally done. Since the trailer is fairly small, this ended up working out anyway.

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The trickiest part of the walls was the nose of the trailer. It has a curved "V" on the front which adds another 1.5 feet of interior space, but since the edges are rounded that made it difficult to bring the flat sections of the wall together. Eventually my friend came up with using 1 in wide boards and using those to go along the curve, then we decided to reuse the original metal pieces that were on those sections to bring the nose together. I'm actually happy with how it looks and eventually want to add more metal accents throughout the trailer.

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Around this point I had interviewed for a Bureau of Land Management seasonal park ranger job and was offered the position for the Summer 2021 term. Knowing that I had to live out of the trailer on my journey out there we quickly rushed to get the trailer into a usable state for the initial trip and so I could finish the trailer during the summer at the much higher paying job. I ended up just using my credit card to buy the remaining wood, cabinets, windows, roof fan, and other items. I knew that with the higher paying summer job I'd be able to continue the project and after working through the winter I would be able to pay the card off without accruing too much interest on it.
Installing the windows was a lot easier than what I thought it would be. Although it helped that we installed the windows and then the interior wall around them.

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The new job started the first week of June, so through May my friend and I quickly installed the rest of the walls, the front cabinets, the kitchen windows, the ceiling fan and a real ceiling (if nothing else than to cover up the insulation). We got it completed a few days before I was set to leave, and my friend gave me the twin bed I had been using in his house to continue using in the trailer.
Due to time and money, we had to be a bit creative with the countertop. My friend came up with cutting 2x4's in half width wise, gluing them together and use the flat cut side as the top of the counter. Considering the rounded nose of the trailer this was also a great way to make a counter fit without having 1 or 2 large pieces of material to deal with. He measured the angle of the nose, rounded out one end of the board, then cut off the excess on the other side. We put some butchers block on it to help seal it up a little, and eventually I'll put more on or finish the top to make it more water/dirt resistant.

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I think with the money I had available and the time we had before I left that we did a fantastic job on the 'mark 1' version of the trailer. I'll make another post with the upgrades I made during summer 2021!
 

grubworm

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louisiana
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grub
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worm
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LOVE IT!!!

im doing a cargo trailer conversion right now myself. you are doing an amazing job and what you have so far is going to be superior to anything factory made.
love the countertops...i did the same thing for mine.
very cool! :sunglasses:
 
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JasKolp

Rank V
Launch Member

Member III

2,354
Idaho, USA
First Name
Jason
Last Name
Kolp
Member #

12037

Ham/GMRS Callsign
KN4TLR
Shortly after I arrived to my BLM park ranger job, I continued work on the trailer. The job would end in October 2021, so I only had about 4 months to finish the trailer into an actual conversion that could be used as a camper.

The first thing I did was decide how to build the bed. I ended up going with a couple cabinets in the rear of the trailer, and decided to build a custom folding bed. This was so I could put the bed up if I needed some more walking room inside the trailer, and so I had better access to under the trailer for any storage items I put down there. During my work with the BLM patrolling through recreation sites and public lands, I found some wood that I would use to help build the bed platform and decorate the rear side of the cabinets in the back of the trailer.

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Shortly after starting to build the bed, I also started painting the exterior. During my trip from SC to ID I found the trailer being a shiny silver looked odd with the ML being painted camo, and the bright diamond plate distracting when the sun was low in the sky due to the light reflecting off of them and into the ML. The most frustrating park of painting the trailer was how I had to do it outside. Many days I could only work on it a little bit because of either winds, extreme sun (which would heat the trailer sides and cause the paint to dry too fast), sometimes rain, or smoke later in the season. Eventually I ran out of time painting it and couldn't put the number of coats on it that I wanted, nor the clear coat, which when I tried to apply went on extremely poorly. One day I'll put a higher quality clear coat on both vehicles.

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It was also this summer where I installed a basic solar system! I didn't have enough money for high quality components, so I bought a Renogy starter kit with 1 100w solar panels, a PNW charge controller, and then bought a cheap 100ah lithium battery and 2000w modified sine wave inverter. I figured this setup would be good for a start, but after my summer season ended I found out the hard way that I needed a MPPT charge controller, and more solar panels and batteries. Originally I was going to build a frame over the roof to install the panels on and any future ones, but after I bought the solar system I was low on money and time so had to just screw the panels into the roof beams.

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By this point I continued building the folding bed. For the legs I cut down some Ikea metal legs I had, and used door hinges for the folding part. I also tightened up gaps that were in the counter top and installed some leftover wood to cover the wall edge.

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Before my season officially ended, I was able to install some indoor/outdoor carpet (because it was vastly cheaper than vinyl planks and covered the ugly treated plywood floor), some hooks, curtains over the window, and some thick curtains over the rear hatch to act as a heat barrier.

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The very last addition I made was trimming my Ikea table and installing it on the passenger side of the trailer. I also made it so the legs can be removed and it can fold against the wall when needed. The fall of 2021 I spent about 4 weeks in the trailer, most of that time diagnosing my solar system. I concluded that the charge controller wasn't reading the battery correctly, wasn't pulling enough power out of the panels, and so I only ever had enough power to recharge my laptop and phone, but couldn't rely on it for steady power.

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And that's the "mark 2" version that was completed in 2021! After my summer job ended mid October 2021, I didn't start working again until December so I didn't make any other improvements until 2022. My goal was to work through the winter months into the spring and pay off my credit card from my initial trip to Idaho and from continuing to build the trailer during the summer. However the first week in January 2022 I caught covid which turned into long covid, so after my 2021 summer job ended I only worked about 3 weeks before the new year, and another 2-3 total weeks between January and April thanks to being sick.

I'll make another post with the improvements I made in 2022! They aren't many because well....sick and broke lol.
 

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JasKolp

Rank V
Launch Member

Member III

2,354
Idaho, USA
First Name
Jason
Last Name
Kolp
Member #

12037

Ham/GMRS Callsign
KN4TLR
LOVE IT!!!

im doing a cargo trailer conversion right now myself. you are doing an amazing job and what you have so far is going to be superior to anything factory made.
love the countertops...i did the same thing for mine.
very cool! :sunglasses:
Thanks!! Yeah I'm kinda surprised with how nice the counter tops came out. A similarly sized and shaped counter top would have probably been 5x what I paid for the materials lol.
 
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Reactions: grubworm

JasKolp

Rank V
Launch Member

Member III

2,354
Idaho, USA
First Name
Jason
Last Name
Kolp
Member #

12037

Ham/GMRS Callsign
KN4TLR
So like I mentioned before, winter 2021-2022 was a huge bust for making money. I had Covid in January which quickly turned into laryngitis, stomach issues, fatigue, ect.

Fortunately during the time I was sitting in my apartment hoping that next week I'd be able to go to work, I watched videos, read forums, and worked on trying to figure out why my solar system wasn't performing like it should be. The major power items I have is my laptop (which draws a max of 140w when charging and playing a heavy game), and my electric cooler (which draws about 75w, and I never used it during my time in the fall). Theoretically the laptop at its average max power, roughly 120w with spikes up to 140w, should have been able to run for about 9-10 hours off of the trailer battery but instead I was getting maybe 1 hour before the battery voltage dropped too low.

I basically concluded what I thought the problem was when I was testing it in the fall: the solar controller needed to be a MPPT controller to better read/charge the lithium battery and to pull max power out of the solar panels.

After I left my winter job in mid April I did some more tests with the old solar controller. I made sure to park the trailer in a more optimal way for the solar panels to get sunlight, and changed a few settings based on what I learned while trying to get better. That helped some but it was difficult trying to constantly calculate the battery capacity so I stayed away from running heavy games/programs on my laptop. The app for the PWN controller would read the battery capacity differently depending on some max voltage setting, which would also change depending on what the actual battery voltage was, and it would never match what the resting/in use voltage capacity reading should be based on charts I found online.

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Thankfully my family offered to help me upgrade some components on the solar since they knew I was having issues. I told them I needed a high quality MPPT solar controller, and went with the Victron 100/50 charge controller. Once I had the new controller installed it was like night and day, suddenly I had power to have my laptop run at more than minimum power, and was even able to play some light games into the night (because I didn't want to risk using all the power when testing it).

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The Victron controller also was able to pull max wattage out of the solar panels for the first time I had seen! The max I had seen the old controller pull was about 180w during the summer, but the Victron on multiple days in April was able to pull 180-200w during the peak hours, roughly 4 hours or so depending on cloud cover. I knew my next step was to increase the number of solar panels for a total of 400w of potential power from them. I originally was going to get 2 175w panels instead of 2 100w panels, but connecting different wattage panels seemed to be not ideal in a best case scenario. Plus the 100w panels were cheaper and eventually I'll replace all 4 panels with 175w panels for a total of 700w of potential power.

I made a video in the spring talking about all of this, and one of my friends saw this and offered to help me with upgrading the solar on the trailer. He had also heard me talk during the fall about the power problems I was having and I kinda think he was maybe tired of hearing about it lol. Regardless, he helped me purchase 2 100w panels, battery monitor, new wires, and a pure sine wave inverter. The modified sine wave inverter I had bought last summer stated it had an efficiency of 90%, but based on my math and what I learned online during Q1 2022, I think its closer to 75-80% which would explain where a huge chunk of my power capacity was going. Plus, upgrading to a pure sine wave inverter would produce cleaner energy for my devices.


Other than the new solar stuff, I reinforced the bed slats as one of them decided to break at the screw because I didn't put the screw as low as I thought. I also trimmed down the table so I had more walking room while it was up, and moved 1 leg to the middle so it was easier to put up and take down. And I tested out some ratchet straps to hold the ramp up so it could be in 'porch' mode. I think it needs steel cables for me to be really comfortable with it, and mounts in the trailer frame instead of using the sides of the spring mechanism.

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So far, I've only been able to install the battery monitor, swap out the power inverter, and install 1 of the new solar panels. Hopefully in the next week I'll be able to get the last panel installed, and shortly after get the charge controller move closer to the battery and the wires swapped out with the new copper ones. I might be overdoing it with the new wires, but I want to minimize any loss in the lines. Some of my family also helped me with a 2nd battery, so once everything is installed I'll have 400w of potential solar and 200ah of battery storage (about 2,500w of capacity).

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Other upgrades I'd like is to add a sink, because the system I have....while it works it was frustrating to use, and my water container takes up way too much space on the counter, so I'd much rather get water from a faucet and have the water hidden in the cabinet. I'd also like to get the axle flipped on the trailer, but I really don't have the energy or money to do that yet. During the spring I had to drive over some low creeks on some BLM land, and each time the back of the trailer would hit the ground. On the way out the rear stabilizers apparently caught on the ground and were ripped apart. Another benefit of flipping the axle for increased ground clearance would give me more flexibility with leveling the trailer. Several times I lowered the tongue as far as it would go and the trailer was still not level.

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And with that I think that's all of the up to date things I've done to the trailer! I'll be making some more improvements soon, as my summer job is ending at the end of this week and then I'll be living out of the trailer near where I have been seeing a couple doctors to continue trying to find something that can help my ongoing symptoms.