The c-clamp I use was pressed rather than cast. The reason being that originally I planned to drill holes (which I feared might crack a cast clamp) and screw the clamp to the conduit. Instead I used JB Weld 2 part epoxy. So after cutting the clamp in two, extending it to my desired length, I then JB'ed it to the conduit.
The GFI in the outdoor box provides two outlets, as does the one in the porcelain socket. A small vinyl shade, clips to the bulb itself, has a Tupperware type lid velcroed to it to hold it in place and add space for the heat to escape, but yet keep moisture off the hot bulb.
Not real fancy, but sure does work.