>>1608505i mean every vehicle is unique, so everyone usually draws up their own plans.
there's literally dozens of .pdf "build your own van" books online you can pirate, plus literally 100s of youtube videos across dozens of youtube channels basically showing and telling you how they fit out their vehicle.
can go with the old classic trick of getting big pieces of cardboard and using that as a template. you can cut that with a pair of scissors or a box cutter super easy inside your vehicle until you get each piece exactly the shape you need, then use it as a template to cut your wood to.
you're seriously overthinking it and overcomplicating it though. you could just lay down a sheet of plywood in the back so you have a flat surface, throw a mattress in and call it a day.
dont feel like you have to start out big like half the trust-fund rich cunts on Youtube do. You dont need shelving or a microwave or solar or any fancy shit.
Start small.
Throw a mattress in the back.
Go camp a night somewhere
During your time /out/, keep a list of all the shit you wish you had, shit you didnt need and design flaws/changes you could make to your setup.
Rinse and repeat.