FF battery mounting in OK battery bag

OK, so I got 8A battery from cabela's and fits perfect inside battery bag(Prowler) in front hull. However I don't want to leave it un sealed in there. Trying to find a box for battery that will fit in bag but nothing works. Any suggestions?? or will it be ok just in pouch alone?
Maybe not even use pouch and find waterproof box? Thought I would use it since it is already there and mounted.
I dunno 

My battery has been that bag every trip for three years and its perfectly fine.  Just be sure to thoroughly rinse it off after each trip.

The bag has held up fine in my yaks, but the zipper pulls tend to corrode. Rinse thoroughly and doesn't hurt to hit it with a little corrosion-x  every now and again. Aside from that, just the battery in the bag should be fine.

See Ya Soon,
Eric / Yakhopper