an RV is one of the most delicate toys one can own. they arent built for even the slightest amount of abuse... but when taken care of properly, they can last a long time.
when one has no clue about RV's, and the unit isnt owned by the user, it can take an unusual amount of abuse....
the reason RVshare doesnt want it in their lineup, is that an older unit is prone to more problems that a newer one is unlikely to have, and with the price of the rental on an older unit being less, and a potentially higher number of repairs, there is no profit in it....
as has been said already by Dutchman, you will be money ahead selling it now and buying a newer unit later, IF you decide to go back to RV'ing after your time away from it...