I would say it is imperative that you pre plan the hell outta this and you can start now!
DO NOT just take off and "wing it"..... You are asking for trouble.
I would start off with a USA map, and maps of each state your visiting (Maps are free with AAA membership, which for $60 is a steal for the services they provide). I would be sure to get familiar with the OB1 app and use it.
How many mpg do you get, round down for safety. Highlight a rough route on the USA map, noting fill up towns, and places of interest you might want to see, Make a list of those attractions. Remember this is a "rough" (not final) route, you will be changing it for sure. Once roughed out, start internet searching for them "Attractions" you listed and investigate do you really want to see that? IF no, cross off, if yes, how long will you be there, say 3 days at the Grand Canyon or maybe 5 hours at the Cumberland Gap museum, whatever you think....Also post here about specific places, contact regional reps and ask questions, get that "local" intel.
All this research will take time and keeps your mind on the trip, which helps get you closer..... And this research can be fun as well.
Think about navigation.... Got an iPad/tablet? Does it have gps? Will you use paper maps only? (That is fine and fun).
Will you need to carry extra fuel or at least a can you can fill at a stop before trekking into an area?
Plan each days food and water, Where will you re-supply? What cooler/s you taking?
What will the truck need mechanically? Are you close to a timing belt change? do it before going, what spare parts will you take? What breakdown items will you take?
Money, how much will will you need for fuel, food/water, entry fees, emergency cash?
Just trying to get you thinking about plans, plan it but do not feel that you are bound by it, you may see a crowd at a place you wanted to see and skip it, you may see something along the way and want to stop. Idea is plan but be flexible, have fun!!! Maybe start a thread about your trip, and you can upload pics of places and write about each day.
2wd is fine, do not go buying a ton of "Stuff" for this trip, you can do so much on very little.
Keep asking questions and enjoy the process, making a bunch of us jealous!
Jim
PS if taking a gun, KNOW each states laws (and some cities)......