Were it me, I would remove all weight from the tires for any storage over 3 months. This helps the tires for several reasons. Sitting on one spot for extended periods causes a flat spot on the tire, which may develop into ply separation in the future; that's the main reason. Cover the tires with either tire covers or cut a piece of plywood to fit inside the wheel-well to block all sunlight off the tires. OR, remove tires and store them in a dark dry place with about 10psi in them.
Make sure there are NO water leaks into the trailer. To cover or not is your choice since you plan to use the trailer during the winter. It would be difficult and dangerous to use any propane appliances when the trailer is covered though.
Do your best to seal any opening on the underside of the trailer to keep mice, ground squirrels out. Remove all foodstuffs when the trailer is unoccupied to eliminate any food supply for such animals/rodents. Consider using one of the non-powered moisture absorbing products to keep interior moisture from developing into mildew and mold.
2000 Winnebago Ultimate Freedom USQ40JD
, ISC 8.3 Cummins 350, Spartan MM Chassis. USA 1SG, retired;PPA,Good Sam Life member."We the people are the rightful masters of both the Congress and the Courts - not to overthrow the Constitution but to overthrow men who pervert theConstitution. "Abraham Lincoln"