My Coachman Mirada has one 12 volt plug on the drivers instrument panel, not very convenient when running a GPS or charging a cell phone while on the road.
The solution was to add a couple additional plugs that would be convenient while on the road. These can also be used when parked as they are connected directly to the coach batter circuit.
We modified the center hump by adding a LCD TV (SEE HERE). When we did that, I installed a standard 120 outlet and also added a small inverter with its own outlet. (SEE HERE)
The logical location for the additional 12 volt plugs was in the lower panel between the two 120 outlets.
I used #12 wire to run the new plugs directly off the coach circuit. These are fused 20 amps.
The source for the plugs was a little harder to find. There were a lot of cheep quality units, but I found these to be acceptable. They make different styles, i.e. 3 plugs, plugs with USB, plugs with voltmeters. CLICK HERE
I bought a standard 2 plug version and installed it low on my panel