Beyond this ^^^^ tho I'd do/did a Square Box.
Zero setup. Park after dark, roll into a full double bed, all setup.
Wake to rain... or snow in the morning, roll out of bed, drive away, zero packup and everything is dry next stop.
Some think trailers are expensive but buy a landscape trailer from Lowes or Canadian Tire, Build an OSB BOX, throw in an old mattress, buy some hardware store gate hardware, find some old plate glass sliders from a 60 year old house, set the glass in lots of silicone, pull a quality tarp over the roof..... better than any tent.... and go.
Buy it all used and you'll have a Square Box Trailer for under $3K.
This was my first version, 5 years ago. I had the landscape trailer and built the OSB BOX complete with doors, windows, roof for $800.
It took 3 weeks to build it. One week was lost to the planning process with Rum and Coca Cola.
Many additions and mods in the past 4 years and this spring the job will be connecting the solar panels, charger, cooler and having refrigeration.
The solar/battery/cooler etc will cost more than the OSB BOX. ALL the hardware is gate hardware from the Home Hardware Store..... nothing is RV $$$ Hardware.
The hardware, hinges, latches, locks 18 pieces, were under $100. The lighting, all LED, 7 lights were under $30... It is grey because I had old grey stain.
Shop when all the out of season stuff is in big bins down center the aisle. Instead of $20 each, items are 2 for $5, batteries included.
Shop smart, refuse to pay $80 for A light or $300 for A window.... my windows were free. I built the doors.
There are great cheap buys if you actually shop for them.
I absolutely love how light filled my trailer is. A translucent roof and BIG windows. The roof is the stuff they use on semi trailers, sold by the foot off a 10" wide roll, I needed 5', $120.
Waking up during a lightning storm is soo cool, the roof comes alive.
The best thing about keeping it cheap is when admitting you made a mistake and making changes you are not admitting defeat. I never expected the plate glass to last, but 5 years later and I drove like a madman the first year stress testing everything, it all survived. When building at home, don't think you have to get it all done right the first year. Build the basic box around the mattress. Get the basics done and go overlanding. The rest will fall into place as you use it and figure out whats next. The kitchen and awnings are next for me. Last years project was the side tables hinged to protect the windows. ALL free old fencing 1x4 and 1x6 with free stain. I bought the hinges, stuff used on stake truck bodies. HD, adjustable, cheap and kinda cool.
I am sure one of these years I'll start with a new trailer.... I really want to match the TJR track so the bed will go from a 60" wide Queen to a 48" wide double..... and use some kind of composite wall with windows I find used or on sale. I'd love to find an old 1960s mobile home with Jalousie Windows. There are several within 10 miles of me. I'd offer $10 each. But this trailer is the super cheap prototype. I never expected it to last 5 years. It might outlive me.
One thing I know, insulating a box 5'x5'x10' is crazy. And I'll never insulate mine cuz I love the dayliight ceiling and big windows. Think hot tent...... if you can heat a tent how much energy are you losing in a tear drop, square drop. Don't over think the zero carbon thing lol, just keep it simple, build it fast, design it to make changes easy.
Focus on two things, zero setup, zero pack up.
