A few years ago I did a cheap fridge for the boat ...and it still works !
Bought a dorm fridge at Target for $60.00 and cut everything off .
Door , casing, insulation
Just kept the inside, grill, thermostat and cold plate Be careful not to cut or disconnect the freon line and to keep the wire+ plug !
Re installed directly in the boat ! Simply cut a door inside cold box to insert the cold plate and freon line and wires. I used duck tape to re-attache the door Should do a cleaner job with epoxy but ...hey It works
Its 110 V so Works at the dock and on the generator Simply plugged on a regular socket on the boat .
Before leaving on a cruise , if I plug it for an hour with a bag of ice inside ,
keeps the beer and food fresh for 48 hours
If I plug it all night It becomes very cold ,freezes the meat , makes ice and then when cruising I just need 20 minutes / day on the generator to keep everything frozen