I upgraded my MLT to a 48qt Rubbermaid regtangular cooler (Walmart for like 15 dollars) but when I tested it I lost several degrees during the hour after letting it preheat. So since I had made the manifold and valve and such I wasn't taking this one back. Instead I purchased a $8 sleeping bag and a three dollar pillow at Walmart. I placed the pillow on top (a little extra insualation for the top) and wrapped the blanket around the cooler. This time, after preheating, I let the cooler sit for over an hour without one degree loss. I'm sure there are other ways out there, but I thought I'd say how I did it. I've seen some put comforters on (SWMBO will allow a lot of things, but not that one) and using a sleeping bag for camping in cold weather was way cheaper. Just thought I'd share this as an idea for others who may have the same problem. An $11 cure for temperature loss. Additionally, the sleeping bag and pillow pack nicely into the cooler after use (Also, keeping SWMBO happy-er).
Tiocfaidh Ar La
"I kissed the bottle, I shoulda been kissin' you"-jawbreaker