When I transported my painted body from NC to NJ in my enclosed, I made a box support frame out of cheap soft pine 4x4 lagged together. They were soft enough to not damage the chassis paint where it touched and then I could ratchet strap the body tight to the trailer floor. No movement.
It did take some time to get onto and off of the frame, but worth the time spent.

The freaky thing that did happen, was the metal crank handle from the roof vent worked free (screw fell out) and fell onto my car. It hit the very back edge of the hood at the cowl and stuck in there. It did chip the hood, but no dent. That was a heart stopping moment. I have since loctited these screws in place.