For those who want to keep the large 'fridge, there are some options besides the Adler Barbour that are almost identical but much less money. Nova Kool, Vitrifrigo, and Frigiboat are the main ones. The Adler Barbour Cold Machine is based on the Danfoss BD50 compressor, which has excess capacity for any plate that you could hook up to it. They do sell a set with the smaller and more appropriate BD35 compressor, but with very small evap plates. The Nova Kool and Vitrifrigo sets let you choose the compressor and hook up to any plate/box. They'll come in at $750-$1000.
Nova Kool uses the BD35 on their 2-door 9.1 cu ft trawler 'fridge, so it should have no trouble with our boxes. The Danfosses can be set to run at different speeds - higher for faster recovery (cold beer now!) but more energy use, lower for longer cycles but less energy use.
The Engels are fine units as well, it's just a size thing, the Danfosses are for bigger boxes.
I've found that condenser units do fine in a settee or locker as long as there is a good vent to the cabin. They're more efficient with lots of cool air, but it's not night and day - as long as there is flow and it's not 120 degrees, they'll be fine.
Mine's in the engine room, on a custom shelf behind and to port of the engine. Doesn't seem to suffer when the engine is running, and if it's slightly less efficient, well it's charging, so no worries.