I built one out of a 16' tandem axle cargo trailer I bought used. I must admit it's a work in progress.
Mirage/Balboa make some really nice toyhaulers built on cargo trailers, but they are out of my budget.
I haul a Yamaha Rhino in it and then my hunting partner and I sleep in it when in the field. It works well, but as stated, could always be better.
Another advantage is that the rhino is always stored inside out of the weather when not in use.
I believe the cargo trailer based units to be more robust then the versions built on camp trailers, but I could be completely wrong.
