The new cars in Europe are required to have ESP for the car and automatically detect the trailer when hooked up and have T-ESP for towing.
Most small European rigs are surge braking and I have had a devil of a time finding electric brake modules for the VW as OEM to take full advantage of this,
If you were to purchase the approved kit to add the wiring from Westfalia the towing module to meet the lase for detecting the trailer, light
status and enabling the T-ESP would be taken care of.
I plan to add this module later along with the Teknosha (sp) P3 electronic brake controller. This will handle braking the proper wheels, controlling the brake and engine pulling to correct for sway and make towing safer. This has been required by law over there for several years.
I figure it can't hurt. It would be particularly nice if the electronic brake control were integrated as well then it would automatically use the brakes
to straighten out the trailer. There are also CanBus ABS systems for larger trailers that do integrate with the car electronics (or more likely bloody great lorry)
Currently I have a converter to handle the brake, turn, and, and tail lights
for my VW. I may have to use this to tie into the Westfalia wiring if I add their kit or I will have to rewire the trailer. The only fly in the ointment is that the normal small trailer plugs and jacks have no electric brake pin specified.