Bill,
Since you do not have a 120 outlet to plug into and quickly bring your  
battery back to full charge, the refrigerator is out of the question for you.  
Again, I think the key is exactly what Elle said, get it cold 24 hours prior to  
using it.
The refrigeration systems on most larger ocean going rigs are not electric.  
The compressor runs off the engine, therefore they keep the engines idling all 
 the time. Some even have what's called a cold plate that runs off boat  
electricity and does draw down the battery bank.
 
Rummy