Probably not enough demand for something like that. I doubt it would have much resell value without a bathroom and A/C except for a small nich market. I would agree with others that suggested a cargo trailer with bunks and a bed.
Neighbor made a camper out of a cargo trailer. The beds fold against the wall and he can haul a Harley or his golf cart. The front part has a small counter with a frig and microwave and sink. He uses 5 gallon water jugs with a pump instead of tanks. He did add a 15K A/C and wire the trailer for electric.
Some of the small older trailers did not have A/C or a bathroom.
