You might look under your coach and see if you have some room some where. And as mentioned earlier, to salvage a lifting mechanism off a pick up mount it under your mh and store a spare there. You might buy or fabricate a bracket that comes off your rear hitch rising vertically to provide a place to attach and store a spare. I spoke to a sales man once who told me they took in a rv that had a complete spare and rim sitting on top of the roof not even attached. I don't suggest that but you might get one of those cargo haulers for roof tops and store your tire in that. The cargo pod would be attached to the roof
Others have suggested running a rear dual with one tire flat. If you're lucky all it did is go flat -- but if it blows -- now you have a bunch of frayed wreckage doing damage with every revolution. (Think of all the plastic parts, air bags, and hoses usually fairly close to tires.) So if that happens you need a change and if you lose a front tire --I'd say you need to have a tire change. You could if you had a jack and was in the middle of no where, one might take a tire from the rear and put it up front but on heavy rigs a single tire in the rear would be overloaded and might not take you far-- but in certain emergencies-- I might try it. Guess everybody has to make their minds up what to do -- call for help & wait or have a plan they can do to help them selves. I think you're right to want to have a tire on hand, as already said, help could be on hand but the right size tire might not be.
Hope you can find a good solution to your problem.
94 Monaco Sig m11 elect fuel inj
95 Jeep toad