On my hybrid in Michigan which has spent 5 seasons stored outside, I definitely tilt the camper, I use RV antifreeze, hot water tank bypassed and anode left loose.
I put duct tape over the exhaust fan vent, heater intake and out-take, refrigerator panel holes and the screen on the hot water tank exterior panel. I don't want any insect building a nest in these openings before the really cold weather hits.
I have used a RV cover before that someone gave me, though I am not sure how much good it did. Less UV exposure?
I also make sure all the penetrations through the floor are well sealed so no critter can get in.