OK...so I got caught in all this snow with my slides out. As of now, there's about 14" of accumulated snow and ice on top of my fifth wheel, with the slide deployed. I tried to get up there to brush...
Here in the Midwest, I see many trailers on RV lots, with the slides out, and covered with snow. I know they are not concerned, as they plan to sell them anyway. I do think if damage was likely, they would discontinue this practice.
If you don't have to move the trailer, I'd wait it out, until it warms up.
It seems to melt from the bottom up, so a little sun, with warmer temps, it should push off easily with a garage broom.