I don't drive my Dak in the snow/salt, but when it's just plain cold I've never had the door frozen shut (I've only had that happen on other stuff during ice storms). But it rarely gets real real cold where I am at, & even though it just recently did, I was driving my GMC due to snow/salt.
On that note, my GMC windows were frozen badly, and no matter what I did I couldn't get 'em down. PIA at MacD's drive through, so I took my heat gun to the driver's window. It might take a while to do the whole door, but you might try that. If you do, it would probably be best to wear rubber boots and stand on something dry. Just in case.