I just lost
a LONG post into the "either-world" and don't have the heart to re-write the whole thing. You may have seen our set up, but just in case...
We used an air cooled Sea Frost unit, with EXTRA muffin fan, insulated ducting, a green LED "on" light, and an indoor outdoor thermomiter. Both it and the BOX are below the floor, between the settee seats, as drawn in the plans. (Both of which we raised 2 "). We like raising our feet, more than clearing the counter, to get inside.
The box was built external from the boat, and though the top and settee floor are lightweight cored composites, the rest of the box is glassed ply and epoxy
gelcoated on the inside. Then it was glassed & a foil barrier installed on the outside.
Sandwiched in there are 1" thick Vacupanels, so I have the equivilent of 7" of foam, even though the walls are only 2 & 3/4" thick. The interrior is ample @ 2 cubic feet.
We turn it to "fridge only" to save amps, and put beverages closest to the plate. It averages between 20 and 40 amp/hours per day, depending on openings and climate.
It has done its job for 11 years now... even through a Trinidad summer. The solar panels
easily keep up, and batteries are usually toped up by noon!
Having seen much of your work Roy, I know that what ever you come up with, will be a work of art!