Re: storing 5th wheel long term
Empty and clean all the tanks, including the water heater. Fill with antifreeze. Remove everything remotely edible. Clean it really well to get rid of the crumbs. Disconnect and remove the batteries; store them somewhere not too hot, not too cold, and keep an eye on their water and charge.
Pests are a question. For sure, make sure there are no big holes (like around the front landing jacks or the power cord) to reduce the chance of mice. Make sure there are no weeds underneath or around the unit. Aside from that, do a search for posts on the pest (mice/bugs) subject, because there are at least 50 suggestions, and none of them work for everybody.
Park the tires on something to protect them. I'm thinking wood or plastic would be best; I seem to remember someone saying that concrete is hard on them. For sure, cover them or otherwise protect them from the sun. As for covering the trailer itself, that is a question. On the one hand, I've heard that the RV covers 'act like sandpaper on the finish' when the wind blows, but I'm a bit skeptical, cause car people have used them for years, and if they caused problems with RVs, wouldn't they go out of business?
Ideally would be one of those aluminum shelters. You can even order them through Wal-Mart. Perhaps cheaper but certainly not as trouble free would be a free-standing fabric shelter. Long term you would need to replace the cover as they rot in the sun, but certainly would get you through the year.