Our winters in Southern Indiana are not as severe as in your area. Take a look at this cover from Camping world and tell me if this and tire covers would help. I will drive it at least each month, snow allowing, and am afraid traditional covers would be too difficult to take off and pout on frequently.
I had the dealer mount a tornado on our black tank. Of course I didn't direct them to where I wanted it mounted so they did the easiest thing possible and mounted it in the middle of the tank inside the hatch (I wanted them to mounted on the right side--towards the rear of the camper).
Despite their goof up I still use it frequently. As far as I can tell it seems to work (I can flush enough to get clear water coming out of the black tank). Tornado Permanent Tank Rinser with Remote Connection - Camco 40126 - Sewer Flushing - Camping World