Bob,
Find someone that knows how to lay-up marine engines and get him to fog both the main engine and the genset. This is easier and better than for the engine than running it.
Get small solar panels to put inside (for protection) the south facing windows to keep the batteries up. You will need at least two. Cover the inside of the remaining windows with aluminum foil if you don't put a full cover on it.
The tires on planks is a good idea and make the planks big so the tires don't sink into the sand/ground.
If the frame has not been rust proofed, get a sheet of heavy plastic to keep the moisture from the ground from collecting on the underside of things.
If it is new enough to be fuel injected, add stabilizer to full tanks, but the rest of the system should be fine. If it still has a carburetor, you want to figure out how to run it dry.
This is all stuff I did regularly for owners of expensive boats before the depression.
Matt