Different HPDE organizations have different policies.... but the tightening-up of camera/equipment mounting policies is pretty obvious. There are been too many suction cup mounts coming off mounted outside and inside cars and sponsors are changing policies to keep it from becoming an issue. Some sponsors require secondary leashes for anything mounted inside the cabin - even if it is physically fastened to some mount. Of course a suction cup mount in a car needs to be very secure AND not block the driver's or passenger's view out of the windshield.
On an E46 M3 - I use a bracket I originally had for an XM/Sirius radio. They make these custom for different models. It has the advantage that its the right size, can be adapted to have a secondary safety leash and can tilt up/down and left/right.
Driver seated view:
Side/rear view:
Shows very small bracket I made and attached to the Aim Solo for the safety leash:
This method is probably easily the same for an E92.