At any rate, this is the route I took. I bought a Draw Tite hitch and a 4-prong harness from eTrailer.com. This hitch fits the stock 2016 car perfectly and requires no cutting of the bumper. The 4-prong harness will get the job done, but unlike Invisihitch/OEM kits, it does not disable the rear park distance control and offer other cool camera options. You have to disable PDC manually.
The install was straightforward but tedious. The video instructions from eTrailer are very good, but there are a LOT of plastic clips on the F15. I took some pictures of the rear bumper cover removed so maybe you can get a better idea of where they are. You need to take your time with this mod in order to not scratch or mar the car.
I have owned a Draw Tite hitch before. And, while they come nicely powder coated or painted, they do tend to rust after many years. To add some protection for this one, I roughed the surface with 0000 steel wool and added a coat of semi gloss Rustoleum paint to this one. Hopefully that will help some. I found the best price for the hitch on Amazon that particular day. Amazon shipped the hitch basically unboxed with a shipping label on it. It arrived seriously scratched. I complained and asked for a replacement, the replacement came in a box and was properly wrapped.
For the wiring, I ran my wires out of the car on the right/passenger side, by modifying an unused grommet and sealing it with black RTV silicone. This way the trailer harness is available by the hitch, and we don't have to do the "close the harness while it is sticking out of the tailgate" thing. It's a little more factory-like. I did have to cut the eTrailer harness to do this, but my solder and heat shrink connections are all inside the vehicle and not out in the elements. The F15 uses modulated signals for brake and tail lights, so you only connect 1 trailer harness wire to the car for both and the eTrailer wire harness module can figure out if the signal is for tail lights or brake lights.
Draw Tite 75600 Hitch Class III 2" receiver, $171.58r
eTrailer 119190KIT 4-prong wire harness from eTrailer.com, $75.95r
Total cost of this mod = $247.53
Total investment in vehicle to date = $4733.53
|Black RTV inside and outside of this grommet|
|I mounted the trailer light controller on the right/passenger side. It fit nicely into an unused spot. But, this required extending the wiring to the left/driver's side tail light.|
|Clips around inner tail light|
|No trimming required.|
|These are what BMW uses to hold the wheel arch trim in place. But, my US-sized pop rivet gun couldn't run them.|