I'm in SW Ontario as well and the trailer gets a cover but the Bigfoot just sits in the yard with whatever snow we get on top of it. I have MaxxAir vent covers on both and they are open all year to allow the whole camper to "breathe". I don't have a light on in either and haven't had any problems. If we get winters like last year where it stayed cold not like the winters of a few years ago where the temps were up and down the humidity wasn't a problem.
Of course the all fiberglass construction and rounded corners of the Bigfoot eliminate a lot of the typical ice build up areas.
Brian