Magnifying glass and curved plastic bottles are useful to channel solar energy for many uses.

Aluminum foil and wax paper are easy to keep around.

A box of rubber bands as they ae versatile to make sling shots or even to keep things together.

A face mesh to protect your face from bugs.

A wide rimmed hat to protect most of your body if standing in direct sunlight for prolonged periods.

Having a whistle to communicate long distances if separated is a great tool. Bullhorn is even better.