We have toppers on all four slides. They remain extended from early May to late September. When I wash the roof, I wash the toppers. No mildew and they are in excellent shape after over 5 seasons. The weight isn't a major factor, either. They were dealer installed and done correctly, not loose and drooping like some I've seen. I had the dealer install a large window awning on the DS slide, but did a small one on the entertainment slide myself. With a helper, I probably could have done the big one.