The truss sections look quite different in person... the are solid, not hollow, so they are about 1/2" thick. I dont think your O clamp will work. I'm using the C-Clamp style clamps to hang my pocket scans. I marked off where I want them to be by wrapping electrical tape around the beam about 5-6 times. So It wont s c r a p e up the steel and cut your hand, also so I know where they go. There are also about 6 or so mount points on each truss section. I hang 2 DJ Spot 250s on the ends, then 4 pocket scans in the middle, and behind the scans I have a TracPod 30 (Elation) moounted facing downward to light the drum kit. Used this set up this weekend for the first time. Went well
About 1000watts total power draw and I have all the cables pre-ziptied to the truss, so I just mount the fixtures and the plugs are there. 1/2 hour to set it up after I carried all the cases in the bar.
--Kevin