Trailer hitch wiring : anyone done it themselves?

I'll be damned. Thanks for the tips. Oh one more thing. Did you need to get anything done to the computer for towing? Disabling backup sensors or anything ? My old vw Tiguan had a "towing mode" that could be altered using an OBD connection.

Hi Dougrobling, could you tell me what size screw you used for the earth connection? The one I have is far too small to use without drilling a new hole.
Great pic by the way, it's helped me out a lot!