I use a homemade clamp that works like a champ, costs pennies each, and can be had in any color.
I went to a big box hardware store and bought a 2' or 3' length of 3" PVC drain pipe. I used my band saw to cut off half a dozen 1/2" wide circles off the end of the pipe, then cut a 1/2" gap in each circle. I left mine white, but you can paint them any color you like.
When I put the table cloth on the table, I spread the gap enough to go over the table top. It works like a champ. I have used them about 5 years now, and if they ever weaken or break, I have enough pipe left to make dozens of replacements.