Protection from the weather is a good idea, but do not use anything that will hold moisture in. It must have ventilation. And, of course, use great care in what will be supporting the cover especially if it will have a snow load added to the weight. And it should have some way to cause water to drain off of it. If you have high winds, consider what will happen when the cover flaps in the wind.
Make sure it is tied down real good. If the wind moves it around, it will wear/rub the paint and when you take it off in the spring your gonna have to do some touchup painting. On corners, I'd put some foam to cushion the edges. Yup, it also has to be able to breath to keep any m oisture from forming.