Yes, you can attach the Gerbing harness either directly to the battery, or to an auxiliary fusebox fed directly from the battery. Nancy's is hooked up directly, and works fine for both gloves and jacket, or for my heated vest.
Clean snow or slush is fun for a few minutes, but a chore after a while, fighting the nanny. The thought of cars sliding into the Spyder isn't too comforting, either. BTW, salt is murder on vehicles!