MN Ben wrote:
How are you busting them off? Must be rubbing too much when raising/lowering the camper. Maybe the material that the stops are attached to is shot. I am sure many on here use a small length of 4x4 (or whatever size) between the cab and camper.
I used a block of wood, painted black, to extend my stops. But this may not work for you if you are already bending yours off.

I used a loading dock rubber bumper on each side. They look just like your hybrid of wood and rubber you have pictured here. I had to re-read your post, to make sure it wasnt a loading dock rubber bumper! ;-)
Garry in AK