I've gotten a lot of free advice this year from mechanics, both vehicle and generator, and this is what I came away with; at least for my climate, which is always cold in late fall and winter, but unseasonably cold right now.
So, the house portion of a motorhome is pretty static in storage. Get it properly winterized, maybe plug up some holes with steel wool which vermin can't stand, and if you are really concerned try the Irish Spring trick in cabinets and spaces to keep them away.
On the mechanical side I was advised by my local generator service shop to run the generator for at least a contiguous hour under load once a month. Not 15 minutes here and there, but a full hour all at once with a load running, they suggested a space heater. What they want is for the generator to get fully warmed up, get the oil hot and all the components under the shroud all up to temperature. With monthly exercising, they did not recommend any fuel treatments. Running the generator was more beneficial than fuel treatments.
For the chassis, that mechanic said something similar. Get the RV out on the road for at least 20 minutes, but preferably longer. Cycle through all the chassis systems you can, so run all modes of the climate control, especially the A/C, which most climate control systems will do in full defrost. Check your lights. Maybe even run your jacks. Getting the rig on the road was essential to getting the engine up to temperature and getting the transmission up to temp, which is something that a lot of people kind of ignore.
I realize this isn't practical for many folks, but it is for me, and makes a lot of sense.