My M1079 hab will sway at night when the wind is howling (and down here, it almost always is). Walking around can sway the rig (even the dog can move it walking around the bed). I'm trying to be careful about left/right weight distribution forward as a result (balancing the captured springs).
Of course, I have to stabilize the hab itself not the truck frame (the truck suspension isn't a factor in my scenario). I intend to make a brace plate and come off the forward (steel) frame corners of the hab. In theory then, I only need two legs. I've found a few random things on Amazon that "look like they might work" but that's as far as I've pursued it.
I suspect that to an extent, I could just secure the hab to the vehicle frame (sort of bypass the captured springs) and eliminate the sway that I'm seeing but I've not tested that theory. Best I can tell, the truck suspension isn't movign at all, but that may be due to the captured springs working as intended and sucking up the motion.