If it were me, I would cut myself several pieces of plywood about a foot square and use them for pads on the roof. I would put each knee and each hand on a square and move them forward as I needed to progress. At your weight, you would be putting less than fifty pounds per square foot that way.
Incidentally, that may be the best looking Falcon I have seen in years. I love them! We had a Horizon (which is the kid brother to the Falcon) and have marvelous memories of our travel in that rig. Ours had the gaucho couch arrangement and we used the bed space above the cab for storage.
Got any pics of the interior?
