I was set up next to a guy at a comp late last year with the easiest solution yet. A folding chair. He was sitting down donig his prep, and I thought that was pretty clever. I know this probably won't work if you are set up on uneven ground, a field or grass, but on asphalt, it worked like a champ.
Mine are standard 1 1/2", 14" long. Need to add end caps.