I am primarily concerned about the risk of losing your camera and more so about the hazard that the rig poses for motorists behind the hero vehicle.
At minimum, replace the open hooks with strong carabiners or with removable chain links. The top carabiner needs to completely encompass that runner on the luggage rack, so that it cannot fall off during a bounce.
In addition, to prevent the bounce/wobble, solidity could be added with two extra ratchet straps (or motorcycle straps) -- one strap tensioned between the camera platform and to the top of the car and the other strap tensioned between the camera platform and the bottom of the car. These extra straps would also increase safety.
Stills from some past F3 projects, all with Leica R's and the 5" Video Assist. Such a remarkable camera: lovely to use, easy to grade, solid in low light, lots of dynamic range...for the money I paid, it's earned its keep 50 times over.
Antoin e reacted to tupp in Sony PMW-F3 with 2500 hours on it. Should I buy it?