Have you considered a Gore-Tex drysuit, or other outerwear made of a breathable, waterproof fabric? I have a full suit complete with integrated booties and wrist/neck gaskets. That's what I would wear, with neoprene gloves and a neoprene head cap. Then I'd top it off with a wide-brimmed hat treated with water repellant. You can wear as much as you want under the dry wear without feeling clammy or wet from your own sweat. Basically I'd dress the same way I do when I go kayaking in icy cold water. I don't ski, but that sort of clothing might be effective as well.
The thing that would deter me is driving on slick roads, part of the reason I now live in the South.