Take a look at your MH owner's manual as well as the manuals for each component. Most of them will have storage recommendations. The best thing you can do for your motor home when going into storage is to change the engine oil and filter regardless of how many miles you have driven since the last oil change. Then top off the fuel tank and use a fuel stabilizer for both gas and diesel. Run the MH engine and generator long enough to get the fuel stabilizer through both engines. While it is in storage take it out and drive it for 30 minutes or so at least once a month. Run the generator with an electric load (turn on the air conditioner) at the same time.
My Onan generator manual has a section on storage that includes draining fuel out of the carburetor and spraying a preservative in the air intake before shutting it down for storage. I've spoken to maintenance techs that service Onan generators and they tell me the most common problem they see is varnish from gas that has gone bad in the carburetor. Don't forget to change the oil and filter on the generator as well. It may sound expensive to change oil after only a few thousand miles but the old oil has contaminants in it that will not do you engine any good if you let sit for long periods of time. Remember that oil is the cheapest thing you will ever put in your engine.
Again, read all the manuals that came with your motor home. If you don't have a manual for some component on your MH (I didn't get all my manuals with my MH) it is probably available for free on the component manufacturer's web site . Most of them will have recommendations for storage.
John and Karen
2012 Thor Challenger 36FD
2013 Fiat 500 Toad