Strolling Home Depot the other evening, I saw these rubber stair treads and thought of this group. I know many use the horse stall mats under their MMM decks when disconnecting on concrete, and one of the "issues" has been the weight of the stall mats when wanting to move them around.
These rubber treads are 8" x 24" and appear to be about 5/8" thick. Not sure it they would work or not, but relocating a few small pieces would be way easier than lugging the mat. At <$4 ea the price is right.