Food
More about the suggested boil-in-the-bag ideas later. If you DO want to replicate what you saw at the demo, be very careful to buy bags that heat okay. Most sandwich bags melt, which is nasty and can be toxic too.
For the purposes of the Expedition Challenge, the hikers must make hot food for dinner and breakfast.
For now, here are some quick links for prepacked army rations. Army surplus do wet and dehydrated sachets.
http://www.ishop.co.uk/item/airsoftadventure/AA-RATION24H.html
http://www.army-surplus.org.uk/outdoor-accessories-ration-packs-c-47_71....