6volt for your bait tank
Buy a battery/pelican box combo and mount directly to your bait tank. My neighbor and I have pretty much the same setup except that he runs his bait tank on 12v battery, the battery life on his 12v is shorter than my 6v.
12volt for your fish finder
I mounted my FF right on top of my pelican box
http://www.bigwatersedge.com/bwevb/s...ead.php?t=7407