We had the Westfalia towbar plus electrics fitted today by PF Jones. The following may be of use to people going this route.
When the fitter removed the rear bumper, there was no metal crash protection beam behind it, just a big plastic moulding running the full width. This sort of makes sense, as ours started life as a panel van, so you don't need to protect people in the back of the vehicle.
This big plastic moulding was removed, and the full width plastic rail (7H0 807 723) was fitted using the 8 clips and grommets. This bit is important as it supports the bumper on its leading front edge.
Then the Westfalia beam was fitted. The fitter said that he had been told that we didn't need to fit the 2 foam inserts (7H0 807 252), but we put them on anyway.
Hope this of use to folks.
Pete