A Thresher Tank should fit in that space nicely. The dimensions are 9 5/8 wide 10 1/2 tall 13 1/2 long. You can attach a 3 piece rod holder to the bait tank that also holds pliers, knife, and some tackle.
-On the launch out I store an 11"x 7.25"x 1.75" Plano StowAway Box full of Irons and hooks, pliers, and lipper inside of the empty bait tank.
The same goes for the return, I pull the drain plug and empty the water before the return and stow it all back in the Thresher Tank.
www.liquidfishing.com