Our go-to solution for freezers (up to 8 cu ft) and iceboxes that will have both a freezer and a refrigeration section - this is called a Spill-over system.
The large flat evaporator (measures 42" x 10.5") can be bent vertically once or twice, or used full-length. The flat evaporator exposes the maximum surface area to the interior of the icebox.
The complete set up includes: Frigoboat Keel Cooled BD50 compressor; keel cooler thru-hull fitting -thread mount (no zincs); 200F Large flat evaporator (can be bent to fit); Guardian digital thermostat and Merlin speed control.
Ideally, a spill-over system should be 2/3 refrigerator and 1/3 freezer, and the total volume of the icebox around 7 cu ft.