I use a battery Jump Box. It has 12v DC 120 AC, air pump and a light. I connect a 10" extension (With 3 heads)to the box and run it under the seat to the fire wall. I plug in my GPS, phone charger and have an extra hole for whatever. The box sets on the rumble floor. I used this in June on a 2,952 mile trip and only charged it once in the Hotel at French Lick. This is simple and doesn't require any special wiring and gives multiple options. Total cost $59.00 and I can use it for other applications when not touring.