Wheel chocks

We went thru several of those flimsy plastic chocks like they sell at Walmart, having your RV roll because it crushed some of those could be lawsuit fodder. I finally saw some heavy black rubber chocks at Northern Tool and those have worked much better.

X-Chocks warn you right in the package that they will not substitute for regular chocks, they are intended to reduce floor bounce and vibration, not stop your RV from rolling.