I liked your idea of flat foil that can be made into a pot.
If you focus on being able to make bark tea, its a good start.
Bark tea while flying a kite, that would be sweet.

You could make some hard candy and make it whatever size and shape you need to make it fit into your kit. Don't bother with chocolate because everyone has body fat. Its carbs you need, to keep the body fat burning and the brain functioning. Just add a lump into each cup of bark tea.