Well, seems the stars aligned, and I scored an OEM (Euro) BMW wiring harness and interface for my car. It has the Euro 12N plug on it rather than the preferred (by me) 13-pin DIN plug, but I can live with that. Now, hoping that the get ready is on the USA cars! Basically, if it is, there's a single harness with two plugs on it that go to the vehicle connected to one for the trailer plug. Then, the interface box gets mounted and it plugs into the existing plug. You have to mount the trailer plug. Other than cable tieing things in place, and reprogramming, it's done! Real slick, not cutting/patching of the exiting harnessess - just plug and play.
I may not have the bracket to mount the trailer plug for a couple of days, but I'm going to try to see if the plugs are there in the harness, waiting for this...here's hoping.
Still looking for someone that knows what needs to be changed in the software to make the system recognize the new box. Some models supposedly recognize it automatically (like the X3), but the instructions say the F07 needs reprogramming.