Horrible day - Is the camper fixable?

I might be tempted to cut the Filon or skin material back to the door area. The join can be a small vertical seam above and below the door opening, and that would help hide the transition, where you might need to have an overlap or use a piece of molding. the woodworking part of it is straightforward for someone with general carpentry skills - but the big "if" is how much bad material will you have to remove so that you are attaching everything to sound sub-structure. Removing what is left of the plywood skin should show you what you are up against. (If the damage goes further back in, I'd be tempted also to completely remove the front piece, and have a good look at the other corner as well.)

Good luck with this and please post pics and updates of your progress!

JIM in NH