I've seen a gauge mounted in the black part between the gauges. That would be a better place if you want to see the gauge at a glance. Can't remember if it was anyone here, or on one of the other sites.
If you mount a cig socket in the fairing panel, just be sure you look underneath before you cut the hole so you'll put it in a spot with enough clearance. Also, get one with a rubber cover so it won't get water in it when it rains.