Making a 55 gallon plastic drum into a Cooling Chamber for my Conical

I just got back into brewing after a 20 year hiatus and love it. I bought a 7 gallon stainless conical fermenter which has worked great over the last few months. I keep my fermenter in the garage which has averaged in the mid to high 60's. However, it is now starting to warm up in Southern California and my last batch showed an internal wort termperature of 75 during the height of fermentation. As a result, I need something to cool down the conical when I brew over the Summer. The conical is too tall and big for my refrigerator or kegerator and I don't really have room for a freezer or spare refrigerator. I liked the idea of the Cool Brewing bag, but it's too short for my conical which is 35" tall. In addition, using it would prevent me from gaining access to the bottom valve to drain trub and harvest yeast. I discovered that a plastic 55 gallon drum should be the perfect size height and width wise, but am trying to figure out how to convert one into a cooling chamber without getting too fancy. I am thinking about insulating the inside of the drum and cutting a door in it to access the valves. In addition, I am thinking about using frozen water bottles or something similar to keep it cool. Beyond the concept, I haven't figured out exactly how to do it. Any thoughts or ideas would be greatly appreciated. And no, suggesting that I go back to carboys is not an option. Thanks in advance.

P.S. I will take photos and post them if this works out.

Ideally you would keep cold water against the conical, as using ice to cool the air in the chamber would be considerably less effective. I am thinking of freezing bags of ice (anything that won't leak) and hanging them in contact with the conical. As they pull heat from the conical, the ice will melt, leaving ice water. Not sure of a good way to swap them out. This plan needs some further thought...