I had a trailer with a slide and got caught in the snow during a fishing trip. The snow melted during the day and then froze into a good sized chunk of ice at night. When we were going to leave I couldn't get the slide in AND couldn't get to a place where I could remove it. It was a mess. By the time we finagled a fix, the slide came in and during the trip home the snow/ice melted and made a real mess inside. Also had other trips during heavy rain storms that created similar messes inside along with issues trying to get the slide out on a couple of other trips. Needless to say, I don't have a slide anymore.
If there is a chance of warmer weather coming you can heat the inside of the trailer and wait until the snow melts. By the look of the forecasts that might not happen anytime soon. I would get up with a ladder and remove as much as I could. When retracted the snow will melt off but if you are ready with towels it shouldn't be a big thing.
Good luck.
2017 Toyota Tundra, Double Cab, 5.7L V8
2006 Airstream 25 FB SE
Equalizer Hitch