The next thing to break after the body mount bolts are the cab side body mounts. They are fuuuun to rebuild! I've done 3. both rears and the front driver side.

I think you're going to want something soft in there to cushion the blows.
My buddy had a pretty good idea to keep the pucks from shifting. If you sleeve the pucks from the bottom up maybe 75% of the way with tube who's ID matches the puck OD. The issue that made it not worth the while was welding the sleeve to the frame side body mount. There is a bushing on the frame side that prevents it that I didn't want to do away with.