I've not seen a unit like this installed on a small cruiser, but if they're similar to the ones used on RVs and houseboats, fitting them inside the boat might be quite difficult.
The propane refrigerators seem to take quite a bit of room up with their top units where heat is vented well above the body of the refrigerator. This structure must extend through the cabin roof as well. Then too, the flame unit has to be near the bottom of the cold box, which could make servicing a bit difficult, whereas in an RV or houseboat, it can be serviced from outside the outer wall.
To fit such a unit to a small cruiser, it would be best to place it at the end of the cabin just in front of the cabin bulkhead with the lower flame access door at the bottom of the bulkhead and through the cockpit.
On a boat the size of a C-Dory, one could set it up as a stand alone unit outside in the cockpit and attached to the cabin bulkhead. This would simplify the placement engineering and move the propane leak hazard out of the cabin and into the open cockpit.
The C-Dory Do It Yourself Custom Pocket Yacht: So many wonderful gizmos and so little space! Think Twice before you slice!
Joe.