Hi! I too picked up a used Q7 for my wife, and I also need a hitch - but in this case for our boat. (BTW, my other car is a 2016 M235i cabrio with manual trans).

Anyhoo, I'm curious if you did any trailer hitch wiring in the end, and if so can you provide (gory) details? did you install the trailer control module? do you have P/N's to share for the pieces you used, and any caveats?

Thanks!

Dave