I know that you can purchase locks for the x-chocks, but once again it would be something to only slow them down. Not a bad idea to remove the wheels...might be a little labor involved, but worth it in the long run. If not all, at least one side. Or some sort of metal stake driven into the ground, park directly on top of it, and secure the stake to your axle. Just thinking outloud here.
2013 Eagle Premier 365 BHS
2012 F-250 FX4 Lariat 6.7 Powerstroke Turbo Diesel
5000# Super Springs