And finally this it what it looks like. You cannot see the cuts in the bumper when looking at the car from the rear unless you bend. The plug is visible and I will lift and angle it a bit to make it less visible, increase clearance and make it easier to use.

To get to this point it took me the whole day with some barbequeing in between and enough thinking time. I am quite happy with the results so far.

This was only the mechanical part of the installation. I still need to figure out the electric piece and how to get the signals to the hitch.

X3 has a weird way of using high frequency pulsed signal for the driving lights in the back (as well as for the yellow lights in the front). It averages to 3.4V but in reality fluctuates between 0 and 12V very quickly. When braking it increases the voltage to steady 12V. I need to get 12V for driving lights to the trailer, 12V for braking and both have their own pin in the plug. I have measured the connector for trailer module and now need to design the electrics to get the proper signals to 7-pin the trailer plug.

Does anyone know where I could access the third LED brake light cable? That would be the easiest way since it is not lid unless you brake.

Attached Images