PS I only fit approved Towbars, Anker are the cheapest for flange type and for removable swan fitting there is a good Italian make which also sells spares, forgotten the name I will dig out some paper work.
Anker also very nicely provided information (all bars are specific to the car they fit) on how to remove the Rear Bumper on the Touran, information sadly missing on the scandal that is modern Hayne manuals, I know I had to remove the bumper what I needed to know was HOW!
In the Tourans case you remove the steel crash bar from under the bumper and the Main Towbar frame fits in its place, with a couple of heavy steel strips bolted inside the crumple zone tubes, again the best advice is loosely assemble then tighten up and torque to the given settings, I wire brush any rust I find and give a coat of alu-zinc paint to stabalise the surfaces, as most bars are given a primer coat I give them some alu-zinc for good measure, bolt heads the same.