As mine has a detachable towbar I put the socket on the rear pillar then bought a short extension, which is fixed to the drop plate. I just plug that into the receiver hitch, plug the extension in, and then my trailer socket is in the normal place. When driving in the mud the drop plate is removed and all the vulnerable electrics are up out of harm's way.
As for the electrics, there's a multipin socket in the rear pillar, also a bullet connector which gives a feed for reversing lights (I think). Mine had three wires running along the chassis for a fixed live and two switched live feeds to the 12S (since removed, although I've left the wires in place for any future power needs in the boot).
Interestingly this was all installed by a LR main dealer, evidently the extra wires for 12S were not installed at the factory as they've had to bolt in extra relays, run wires, and add a couple of inline fuse holders connected to the battery. I've since reused one relay for extra horns and the other for a power socket in the boot.
The remaining bullet connector is a fixed live IIRC - the instructions on the RAVE CD for fitting the auxiliary power socket in the boot make mention of it. I didn't bother using that as it would have needed a wire run the length of the car to activate the relay, rather than just some new connections in the ex-12S wiring.