Insulation
As far as insulating the ice box, I removed the drawers and the framing (4 screws) to gain access to the outside of the ice box. I insulated the outside of the box on the three sides I could reach as well as the bottom with foam board and duct tape. Then I routed the drain hose to the center of the bilge area and put a stopper in the end of the hose. This keeps the heat from the engine compartment from travelling up the hose into your ice box. You have to remember to drain the box once a day, but it saves the ice. I can get 3 days plus out of 2 blocks of ice during the summer this way. I looked into refrigeration too, but the significant battery upgrade, difficulty in retrofitting a higher amp alternator along with the cost of the unit and cold plate steered me away. Also, with a refrigeration unit, you'd need to do some upgrading on the box lid to avoid condensation on the outside, additional electrical load, etc.