I put an additional 12v socket inside the top-opening storage cabinet next to the stove and fridge. The cabinet I am talking about is the one that gives you access to the water tank and pump. 

I used a "side-mount" 12v socket and mounted it to the left side wall.  The cabinet door can still be closed, even when the fan I sometimes use is plugged into it. This location is convenient for most applications, and I didn't havw to do any cutting or drilling on cabinet faces.

The socket is connected to my second battery located under the driver's seat. It was easy to sneak the wires behind the kitchen cabinet. If you do this, keep the wires away from the cooling fins and fan at the back of the refrigerator.

Good luck.

Michael