Bill, this works very well. Thanks for the suggestion. The only problem is that the feet on the middle stand protrude into the stretched fabric. But I think a C-stand plus a magic arm with a clamp on the end ought to give it the right distance (I've yet to try this).

Now that I recall, I did use a grip head and a 5/8" rod to prop up my background in the center so the legs wouldn't protrude.

Two Hi roller stands, a couple of speed rail ears, three in-line (straight) speedrail couplers and four (4) six foot sections of 1 1/4 inch speedrail.

That should do the trick. All can be rented.

Use #2, or #3 spring clamps to hold the muslin to the speedrail.

I see people talking about mafer clamps, those aren't good for holding pipe, as the jaws are too narrow and have too much rubber padding. Cardellinis, or Matthellinis hold much better. Or use something like a Cheeseborough, found in theatrical supply stores, rental houses. Manfrotto have a good line of clamps similar to cheeseboroughs.

You are best to use a larger stand, like a combo stand, or a Hi roller and a 4 1/2 inch griphead, with the afore mentioned speedrail, that way none of that sh*t's goin' anywhere.

If you've got dancers dancing on it, you'll want to tape the front and sides down. You'l need the heavier duty set up if you've got people dancing on the drop. that will prevent injury and lawsuits.

Even better is if you can rent a studio with a hard cyc and light it interestingly, or paint it. That way you've got tons of room and the dancers can do whatever, just keep them out of the cove (curve). Often that bit is delicate and a foot through the cove is expensive.