Winter Storage - Cover at Home or Store at Indoor Facillity?

There are always risks. Leave it outside, and besides the potential scratching caused by a cover, rodents could cause severe damage or even a fire. Winds could cause an object to hit the coach and damage it. I think your best bet is to drive it to Florida and stay with it during the Michigan winter! Seriously, wherever you park for the winter, there will always be risks. You apparently have been prudent finding a winter storage facility, and besides being sure you are adequately insured, there is nothing more you can do.