I found that my freezer and refridgerator could benefit a lot from better insulation. I started to disassemble the galley area to add insulation and gave up when it seemed too complex to get where I needed to go. I bought a roll of 1/4 inch thick reflective bubble wrap insulation at a home store. I lined the bottom inside of the freezer and the sides as accessible. Then when I can I lay a blanket of this stuff over the top doors. If I leave the boat a few days I can add a layer inside the fridge door also. I find that this cuts down on power use and also seems to greatly reduce the frosting up at the cold plates. Not really as elegant as what I wanted to do but it works and is easy to do
A couple of years ago I went to an air-conditioning store and bought the black insulation that they use on conduits and elsewhere. I placed a layer of this foam on the bottom of the fridge and freezer and also cut the mats so that they completely covered the top counter where the doors open. It didn't look pretty, but it made an amazing difference in energy consumption. I now dispence with the black covering on top but still use the covering inside the fridge.