If you are running 24 volts directly to the camera, then you're probably not going to be using the coax to supply power. (there are cameras where the power is provided over the coax, some Sony cameras come to mind.)
You might also look at using baluns and cat5 for the video runs, they may perform better than coax over a long distance.
The catalog that I'm looking at advertises some of the active baluns as being good for 7800'+,
and the passive baluns at 1000', and 1968' with camera power on the same cable.
