A MH isn't a car... You will buy a new unit, but you will get one back that has been used by people potentially clueless, ignorant, or outright just malicious. The money to be made is not that much, especially with all the stuff that can break. There is also deprecation to keep in mind... and it would take a lot of revenue coming in to offset that.
Also, there are legal issues. Say the renter trashes the rig, and has no insurance. Yes, one can sue, but it might take years to get a verdict, and the renter will just give you the middle finger, and will never pay the judgement. Or, the renter crashes the RV, doesn't have insurance, and the other side sues the owner of the rig for damages.
Too much hairy stuff that takes a lot of legal stuff to sort out for me... I'd go elsewhere if I wanted an income source.