Try getting an old mounting screw from a tripod. Get a piece of two inch platic pipe-piece of rain water pipe say or box section about two foot long- drill a hole big enough in it, in the middle of the pipe- to allow the thread of the mounting screw to fit through. Then hold the pipe with the hole downward, and with a ruler and some blue tack holding the mounting screw onto the ruler pass the ruler into the box section until the thread meets the screw. Then mount the camera onto the box section. Then using heavy elastic or duck tape mount the pipe to the bars of the roll cage. The flat edge of box section will prevent the box section from rotating as it will be in contact with the cage. If you can't follw this don't worry -I just made it all up as one possible solution.