I've used a RAM mount to fit my Gopro to the top of the luggage rack and that gave a nice over the shoulder view of both me and passenger.
For us as well but fitted to the crossbar for the harnesses behind us.
Fab'ed a mount clamp and used ram universal mount bolted to that and then a bone and then the Ram GoPro mount.
One annoying thing the Ram GoPro mount has a screw rather than a GoPro Thumb/finger screw.
The threads are not compatible and the nut does not fit in the recess of the Ram GP mount not insurmountable but a pain. Very adjustable. Long and short bones and double balls to extend.
