The climatic and storage conditions on most commercial or recreational life raft packs are more extreme than those in a car trunk in a southern summer or northern winter.

I've looked into this issue. My conclusions were that "lifeboat rations" are the only foods I'd rely on for several years. So they are my core food supply. Dissappountingly, the packaging doesn't seem to hold up all that well to a lot of movement, vibration or handling, so mine got an extra layer of aluminum foil and a vacuum pack.

There are lots of supposed "official" MREs out there, of varying quality. I conservatively count them as done after a year, or one full season of high temperature trunk storage. I usually have only one or two in there. I also have a small amount of COTS (commercial off the shelf) food items in my pack. My experience with long distance backpacking has taught me that, ounce for ounce, peanut butter is a good choice; it will keep you going a very long way. Likewise, my work in disaster zones has shown me the value of a little electrolyte drink mix for working in hot environments. The COTS stuff also get tossed each winter.

I carry 3 liters of water and ice in an insulted Camelbak that gets replaced every third day, a liter in a Nalgene bottle in an outer pocket of the BOB that routinely gets dumped and replaced whenever I think of it, and several commercial water bottles for general use, along with another empty 3L water bladder in the BOB itself.