I ordered mine with the extra 12V socket option, and looking at the socket in the boot it moves a bit like its just clipped into the plastic inner cover on the boot lip. So there may not be a bracket - I think the socket would be more rigid if it was screwed onto something. Also, it was an A$100 option (i.e. only about €30 in Germany), so there can't be much involved in fitting it. This means the wiring is likely to be in the standard harness, and the socket the dealer quoted you may be the only part you need to buy.
