What to learn the home built truck conversion?
Do you have lots of money?
From experience.. the tuition is way, way, higher than you will ever get any kind of return on.
Here's the short course... shop Racingjunk.com, find a truck conversion that is close to what works for you, buy it for 15% more tan the guy is asking for it.
Bring it home, rip the carpet and upholstery out and change it to your taste. Maybe even have a local cabinet maker change a cabinet or closet for you.
The object is to enjoy your rig, not build it. Get a 3 year head start and buy one and remodel it as needed, on your own time schedule.
Banks do not finance dreams and old wore out Uhaul-trucks that you intend to dump 20K into.
RV parts are expensive, go to your local RV store, get one of those big 2" thick parts books the like to give away. start adding up, black tank, gray tank, toilet, shower stall, water heater, water pump, inverter, charger, battery pack, air conditioning, flooring, awning 12V lighting, I could type all after noon and have a 1/2 thick stack of recites to show how 10-25 dollar items add up to100 and 1000 dollar bills VERY FAST!
don't mean to rain on your parade, but I've been there, bought the t-shirt and $90,000 of parts and labor to finish mine.
Rumrunner RV | Blizzard's Road Eating Rumrunner