I have a soft roll up tonneau cover for 4 Canadian winters now. No problems whatsoever. Just don't leave 2 feet of snow on it. Only takes and extra minute to brush of fresh snow every morning after scraping windows.
I also have Bridgestone Blizzak studless winter tires on a second set of wheels. This is my first set of winter tires ever and they definitely perform better than all seasons. Unfortunately can't compare them to anything else.
If I was having only one set of tires in a snowy climate I would go for Duratracs based on excellent reviews and recomendations.
You already have 4x4, maybe thow 200lbs of weight in the back, bring a shovel and drive according to conditions and you'll be fine.