I can't believe the Gen 3 doesn't have a 12v power outlet in the back...I see there is an option for one if you get the rear centre armrest, but otherwise!!!! I think it is obvious to have one back there and was very surprised to find none when I went to plug in my koolatron fridge!! Anyone put one in back there themselves??
I've been thinking of adding this at the rear of the front console, using the same parts as the outlet inside the console (with spring-loaded cover plate) - assuming there is room in the open space under the console. It would be about $40 in OEM parts.
I put one in the back of my Gen II, it was very easy too. Sorry I know nothing about the console of a G III.