No firearms.
With a fifteen mile hike ahead, I'd use the pack space for extra water, jackets and food.
Fifteen miles of hiking with full packs on the back of two middaged persons on a hot day -- that's between 8 and 12 hours of hiking. Knowing this we will need water food and protection from the elements.
Ala heinlein, I'd rather move stealthy than bold.
TRO