I too knocked mine off the blocks last year and dropped it on the bed. I had 6 x 6's under the landing gear, but no chocks behind the tires. As I was pushing under the king pin I managed pushed the trailer off the blocks. It dropped the 6" and just barely made contact with the bed rails. The incident left a small crease on both sides of the bed. Fortunately, there was a metal strip on the camper where the cap joined the body. It took the full brunt of the impact and did not crack the fiberglass on the cap. If I didn't show you, it would be hard to spot the damage on the truck or the metal strip.
But it did teach me a lesson! I do not use blocks under my front jacks now, I bought a 10 foot 2 x 12 for the jack pads to rest on at home, and I make sure the king pin is high enough to easily slide into the hitch. I am thankful the damage was minimal, to both the trailer and truck bed.
2011 Ram Truck 2500, Crew Cab, 6.7L CTD, 4X4, 3.73 Rear