wrote in message ...
Was it me, I'd run a laminated beam of 2 2x4s across 6 or so joists,
Attaching it at each joist with a metal hanger, and put solid blocking
between the joists.

Bungee cords- 3 to 1 weight ratio.
Screw in a half-dozen up-eyes, run your cords through; work your ass off.

Chas