Is your box waterproof or could it be made so?

Waterproof? not sure on that I do have a gasket on the cover to make it somewhat water resistant. The D/C receptacle needed to be sealed up on the inside, for that I used hot glue this also secured the the wires inside the box.

Any idea of battery life on your set-up?

Battery life? not sure, batteries are the 18 volt Hyper Lithium Ion rechargeable, I'm pretty sure they are lighter than 8-10 AA's (don't have a weigh scale) and takes up less space. Maybe someone more tech savvy :-/ could do the math and chime in on this.

My score with this set up was mainly dual purpose rechargeable batteries @ 18 volts and eliminating the amount of AA batteries I had to bring while camping -two sets (16) f/ the f/f, 2 f/ head lamps x2 (guy in front), an another 4 f/ a hand held GPS which I may not bring given that a map doesn't requires any batteries.(thats was 24-26 AA's)

I'll be testing this set up on fishing opener while Lake Trout fishing. Any one ever check out Kemo?