I've never bought or considered an ex-rental RV, but judging how people use/mistreat rental anything, I'd have some serious reservations. The price would have to be very, very competitive.
A gas rig with over 100K, would be well used. At one time, gas engines wouldn't last more than about 100K, but they are better built now. (The same is not true for diesels as they can go 300K plus before needing an overhaul.) The same holds true for transmissions. On the other hand, if the price is right, the cost of a new (to you) engine/transmission from a salvaged RV might be a logical option.
If the rig has over 100K, the interior furnishings and appliances would also be well used. Keep that in mind.
Good luck.
