Nice write up and i may consider doing this. but why not just use a bolt that screws into the tow hook opening? You could do some trial and error with length and just use a nut on the front and back of the plate holder for the correct distance out from the bumper. Maybe for version 2.
2013 EB 335i xdrive | Msport | Coral | DHP | ZPP | ZCW | ZTP | 400M | Coded | MPerformance Bits | M3 Grills | Painted Reflectors | BMS Exhaust Tips | LED Turn Signals
2011 JB 535i xdrive | ZPP | ZSP | ZCW | 6FL | NAV | 331s Square | MPerformance Spoiler | M5 Grills | Painted Reflectors