lets just cut to the chase... spend 2-4 weeks on Racing junk opening and reading all the toterhome and motorhome ads..
you will find that 99.9% of the rigs for sale are being sold for pennys on the dollar, want a high end 300K truck? they are for sale for 180-190k
you want to build a low end home built 30,000 truck? it will cost you in the end 50-60K and if you want to sell it.. it wont sell till you mark it down into the low 20's
since you have the shop and the tools / talent,, buy a truck in your price range, then re-carpet it, put new beds, curtians showers, crappers and couches maybe install a modern tv or 2, and paint a stripe or detail on the outside that says "you".
you will save 10's of thousands of dollars, and 2 years build time. the adventure of going across country to buy it and bring it home will be more exciting than 300 trips to menards or home depot too!
been there bought the t-shirt and am 25-30k upside down on my home built.
regarding balance as mentioned above, the whole truck has to be planned out to the nearest 500 lbs on the total finished weight. you start with the front axle, because it is non-negotiable, it is what it is and you cannot exceed it. that tells you max on the front. The box and all the contents must be decided into 12" locations to start all the calculations. Once total weight is determined the fulcrum point of the rear axle will be established. you need to have weights for all the tubing, the tanks the appliances everything, as well as exactly where they will be located. By running tandems, you could put much more on the rear thus taking it off the front. That is why class C mini-homes have so much tail behind the axles to teter-totor the weight off the already maxed front axle.
it gets complicated, its not impossible it just takes time, you learn new skills like wiring gen sets battery storage and 120 ac is not exactly like wireng a house or a car, their are special grounding considerations, just a whole lottof stuff that if I were to do it all over again I'd go with racing junk and let the pros build it and let the first owner take the huge monetary loss rather than me.