Over the winter the van was parked up behind the bunkhouse. Snow accumulated on top of the van eventually deformed the roof about three quarters of an inch. Everytime it rained this depression filled up with water and when the van started going downhill the water gushed over the windshield.
After removing the headliner and pushing the roof back into place, I decided to take steps to keep the van roof from being damaged again. Instead of parking behind the bunkhouse the van is now parked on the hill up to the bunkhouse. On January 3rd I shoveled some snow off the van's roof to lighten the load. Depending on how much snow we get, I suspect that the van roof will need to be shoveled several times this winter.
I believe that weight of the snow is not the real problem. The roof was probably dented by a heavy load of ice that builds up at the bottom of the snow pile. If I can keep the snow from accumulating over the winter there should be less ice and the van should be ready to go in the spring.