I hope you have this resolved but as I've just done this I'll post what I did. Basic trailer lights worked before I made any changes with odb11 but I made the following changes:
1) Connected to the car, click the menu (blue circle) at the bottom right to list the control units, the towbar module (69) had a yellow circle (it was visible but not active), click on the pen menu (blue circle again) at the bottom right, Scroll down the gateway list coding and check the towbar module box, back in the Control Unit list and the towbar should now be green.
2) Select Parking Assist, Select Long Coding (I'm not 100% sure about this but a menu with 5 or 6 settings should appear and trailer hitch should be one of the options), Select trailer hitch and change to removable hitch, long press the green tick to save the code, enter the suggested 5 digit login if required.
That's it, parking sensors are disabled and a picture of a trailer appears on screen when the trailer is plugged in and I select reverse, the fog light on the van is also disabled as expected.