Take the factory reverse sensor housings from the bumper and fit them to the BSM mount. 

Take note that one of the housings has a champher on the face and the other has a rounded face. The housing with the rounded face is placed closer to the outside of the bracket next to the BSM. 

Feed the reverse sensors through the backing mount and fasten them to the housings using the clips. 

Rivnut the BSM spacer and fasten the BSM using x4 M6x10 button heads. 

Mount the spacer and BSM to the face mount plate using M6x12 button heads. 

Take your BSM mounts over to the bumper

Feed the taillight loom through the hole in the bumper and fasten the BSM backing mount to the taillight bolts using the supplied hardware. 

Place the BSM face plate in front and fasten it to the tray using x2 M6x16 buttons heads with nylocs.

Feed the BSM plug through the back of the  mounts and plug in to the BSM. 

Fasten the BSM mount to the rest of the brackets using M6x16 button heads with antiseize. 

Using M6x20 button heads with antiseize bolt the plastic cover plate to the bracket

Fasten all the button heads. 

Your BSM and reverse sensor brackets should be looking like this. 

Cable tie the loose BSM looms securely to the tray away from any hot or moving parts.