You could add wheels, (solid) or frame sliders, but whichever you choose, mount them to the frame just in front of the bumper, not the bumper itself. As stated above, the bumpers aren't much more than steel storage containers for the stinky slinky.
If you add them to the frame, then it "should" do what you're wanting to do, which is prevent bumper and / or frame damage. Keep in mind, it will take weight off the trailer wheels, so there may be some creaking and popping throughout the camper as it flexes when applying pressure to an area it isn't used to.
Me, the wife, & 2 daughters (9 & 4yrs old)
2019 Palomino Puma QBSS
2015 Silverado LTZ / Z71 w/ many upgrades