I recently installed two 12v plugs on "Katmai."
I'd been thinking about where to put them for a while, and was tired of using the 'splitters in the only available 12v socket by the helm. After giving some thought to my intended used (laptop, XM radio, fan, chargers for cellphone, etc) I decided to mount them in the cockpit bulkhead near each battery. Each socket is fused, and in that location the wiring to the battery was a breeze.
As for the "big green mungy thing," we're currently in AZ ... and there is no Arizona word for "Mungy!" ...but 104 degrees today, and 109 tomorrow (we're at 3500' MSL!!) makes me want to return North!
Best,
Casey