Last year I added a full sine wave inverter (Xantrax ProWatt) with remote switching and power change over relay to the rig.
Besides allowing me to use the high-rate USB chargers it allows us to plug in a small crock-pot and cook dinner as I drive down the road.
Now current (2014/2015) rigs are starting to appear with 110V outlets that have built in 3amp USB chargers.
Our 2012 rig came with what they called a "clock and universal charger". It has micro-usb, mini-usb, full-usb, and several types of "cell-phone" jacks. It runs off either 12VDC or 110VAC.
