We stuck a magnet on adjacent corners of the plate, which proved plenty strong and also allowed us to easily lift the other 2 corners to remove the GoPro. NOTE: Be sure to place gaffers tape over the magnets so they don't scratch the paint. We also used the white plastic spacers that came in the kit, to build up the other 2 corners, so the plate would sit flush.
Here is link to the finished video: Mini Motoring School