A friend had a tree fall on her Class A. They thought they could fix it
(they didn't have insurance for that), but there was more damage than first seemed, like the big front window won't go in right- frame bent out of shape. whole thing got to be a handyman's worst nightmare the more they tore out the more damage was now exposed.
Parting it out is peanuts for money, selling the furnace etc. Probably why they would like you to pay that 20%!!! Run away! :(
I agree with above. Be glad you have the full insurance and enjoy your new rig.