Will they allow you to bury two small junk car tires? Not a joke. If you can do that you can do the same thing as I have on Quicksilver. Bury tires or even 2 feet square 1-1/8" sub floor grade plywood.
Drill two holes 18" apart in the center of each. Half inch NYLON rope will hold your van.
Bury squares under 18" of dirt or sand. With sand pour water on top to compact the sand.
Sticking out of the ground will be two loops you tied into the above-ground NYLON rope.
Attach one cargo ratcheting load strap to each loop and the other end to the frame of your rig.

Keep pulling the lever ratchet-ratchet-ratchet, until the strap tightens.
https://www.harborfreight.com/catalogsearch/result/index/?dir=asc&order=EAScore%2Cf%2CEAFeatured+Weight%2Cf%2CSale+Rank%2Cf&q=cargo+ratchet+strapQuicksilver laughed at a 150 mph broadside hurricane. It didn't even quiver.