When I had my '01 F650GS, I put the socket (a marine quality one) on a short lead, so that it just hung loosely, tucked behind the radator cap when not in use.
When the GPS was on, I just lfted it out and stuck in the GPS plug, so both leads were nice and short.
The wires came direct from the battery, with a 2 amp? inline fuse connected to the postive terminal and just tucked through to above the rad through a gap at the front left of the battery holder. (I guess it'll become obvious if you take a look).
Incidentally if you want to get to the battery you only need to undo six screws holding the centre panel. There is sufficient flexibility in the plastic side panels to simply spring the tabs out of the centre panel, with a gentle bit of wiggling. You don't even need to take off the oil-tank cap.
Reverse assembly is similar, just flexing the side panels a little to get the tabs into the slots. It's a very quick job to carry out especially if you have a screwdriver with a selection of 'torx' bits rather than the "L" shaped tool in the tool-roll.
More info at the
F650 website for UK & Ireland owners
Cheers, Trevor, Bristol, UK.