Barring the ability or space to put your rv in a garage or under a carport, a cover will be much better to winter your rv under, than being out in the open. I would recommend an ADCO cover. The delux series is made for snow and is water resistant. It also allows air to flow through without letting dust or dirt through. If you put damp rid containers all over in your rv, having a cover over it will not cause mildew or attract rodents. My cover cost approximately $350 and should get at least 3 to 5 winters out of it. For me, $70 a year is worth avoiding the potential of freeze and thaw issues that create leaks from the roof...
Steve & Beth - Milton, New York
2006 Monaco Knight 38 PDQ
Ready Brute Elite-2008 Hummer H3