Have you allowed to build up on your rig before climbing up and clearing it off? Got real worried with 18+ inches of Sierra cement and finally did it. Wasn't easy but what a relief!
The snow load on RV roof topic comes up quite often. Over on nuwa forums some years back someone posted a picture of a Denver, CO area RV dealers lot full of trailers/motor homes with over 3' of snow on their roofs.
How heavy is snow....how heavy is a rock....it all depends