Just as an FYI, hanging a Halide pendant from a 20ft ceiling is no different than hanging it from an 8ft ceiling. For hanging round pendants, a single black slender aircraft cable (kinda like bicycle cable, only rated to around 2000lbs) connected to an eyelet ring threaded into the ceiling, with the wires running up next to the cable, or some people do a little spiral wrap around the cable. They make some rather nice looking flat black tear drop shaped hanging pendants. Perhaps 2 of those in a 400watt variety would enable you to have all the light you would need for most anything you wanted to keep.
Any lighting type can easily be made to connect to a metal frame work. If you decided you had to have it supported by the floor, you could take some measurements and draw up a simple structure on paper. If you were local you could take that to me and i could weld up the frame for you in a few minutes for about $20 in time and materials. Since you aren't local though, you would likely be looking at a minimum welding shop labor time of $35-$50 to have it built to your specs. Depending on how elaborate your design is, it should be something that any welding shop could easily make for you in 20-30mins.