As I’m sure you know, the problem is the road salt and chemicals, not really the snow and rain itself. Regularly wash your car through the winter and I think you’ll be doing about everything you can keep corrosion at bay. I lived in South Dakota and now live in Wisconsin, so I totally understand the concern. Also, any time you get a rock chip that exposes the metal, fill it in ASAP to keep moisture and junk out of the "wound." In most modern vehicles where I’ve seen rust, it appears to start where deep scratches and rock chips were left exposed. That you live really close to work helps. If I were in your shoes and looking to keep my vehicular investment in top condition, I’d look at maybe just buying a winter beater to get to and from work, instead of buying the paint protectant.