The other big issue is making sure you have enough power while you're on the go. EcoxGear has a couple solutions. First, their waterproof powerbank is a small and convenient external battery that's good for a couple of charges.
If you need more power and want a little music for later back at deer camp, EcoxGear's new EcoPebble Powerbank has enough juice to play music for 50-hours straight. It comes with two USB sockets for charging your smartphone or hand held GPS. I also comes with a seriously bright LED flashlight, built in. Of course, the entire devices is waterproof and rigged with a carabiner to hang it on tree limbs or a backpack.