Best RV Cover for winter weather; snow, ice, cold temps?

Actually any weather, Summer or Winter, will cause much damage to an RV. Before I had indoor storage, I used an ADCO cover for a number of years. If you add protection at sharp corners and keep it rather snug, a cover will last a number of years.

The only negative that I have seen was a very, very slight paint abrasion at a few spots.

If you want paint to fade, caulking to crack, decals to curl, tires to rot, seals to dry up, plastic to yellow and parts to rust, then just pretend that the RV was made to be exposed.