No problem
I used the Westfalia wiring kit, which includes and ECU and interfaces into the other systems - i.e. ESP, ABS, Suspension, parking sensors etc.. Much better than a bypass relay and splicing cables which may cause lots of issues!
You wont need the charging wires then, just the 13 pin wiring kit (and probably an adaptor to 7 pin for your trailer?).
See the install instructions here:
http://www.westfalia-automotive.de/f...6391101-01.pdf
Edited to say: you will need to get the car coded for the towbar module, either VCDS or a dealer/specialist should be able to do it in about 10 minutes!