T.R. I ran into the same issue of cab clearance with my 08 F-350 and a 2000 Alpenlite Cimarron 850. The cab clearance was only about an inch. I added 4 – 8 foot 2 x 6’s screwed in to the bottom of the camper floor. In addition to adding the necessary additional 1 3/4″ of clearance to the cab, it also provides a sturdy beam base for the floor to rest on when removed from camper and resting on saw horses. I hop in and out of the camper with confidence now.