I just built my own RV, as I needed a toy hauler, but manufactured toy haulers are HEAVY. I started with a new 14 foot cargo trailer, pulled the plywood off the walls and went to work.
The bed folds into the wall so we can take our dual sport motorcycle camping as well. I built all the cabinets, installed AC and DC throughout, along with an 2000 watt inverter, insullated walls, ceiling and floor, and the trailer is self contained, so we can go for as long as we want and not worry about the essentials. Weighs 3400 pounds loaded for camping, including the motorcycle, so the Jeep tows the trailer well.