One of the guys I used to fly with carted big models, 170cc aerobats in his van, and set up a few custom mount points on the bottom of his van.
This was fine for everyday flying but if he wanted to do a competition in another city, he had a problem whenever he wanted to shift the mounts.
After some head scratching he just plopped a chunk of 'dog mesh' fencing (3/16" Wire with about 4" squares) on the bottom of the van.
VOILA! A hundred different tie points and each square chocks the wheel in every direction.
EASY!