I have built the greatest portion of this on my own. I'm having an absolute blast. I love building things and have built many things (hot rods/race cars/dune buggies/custom golf carts/ etc). So this is right up my alley. I also bought an old travel trailer for the doors/windows/slide components. It has worked great so far.
However, If you don't really LOVE the process, I would just buy a used unit and go enjoy it.
My biggest problem so far is all of the little things that I think I'll do different on the NEXT one.