Of course, there is the fact that a renter can claim to have insurance, and then destroy the RV... then you have to sue him. Having seen similar behavior in real estate where a tenant destroyed a renthouse, but had no assets to make a lawsuit worth the time and cost.
Yes, it is doable. No, the time, trouble, and the effort needed to have lawyers write up the mountains of paperwork needed to CYA and protect your rig wouldn't be worth it. Cruise America is able to do this because they have vehicles specially built and have heavy buying power... as well as very well written rental agreements.