I am concerned about the heat in a trunk and its affect on lifespan of any food stored there, this relates to MREs since they are known to be heat affected.
Though I am unsure about everything ...most things are adversely affected by heat. Anyone know if freeze dried stuff is as sensitive as MREs ?
One answer would be to rotate it out frequently.... another would be maybe storing food in an insulated container like an empty ice chest ... that might slow things down, but eventually the heat will "soak in".

Aside from not storing lots of food ... and going with rotation and things like Mainstay bars ... I'm not sure what else to do.
-KW