Hi Gillie - Yea, there's a drain hole in the inner stringer. You might want to consider putting a WATERTIGHT hatch in the splash well to gain access to a lot of space in the bilge. I mounted my trim tab pump on inside of inner stringer, and fuel Racor filter is mounted on side of bait well. You can also access more space between outside of baitwell and hull . . . it's a dead end cavity where stuff rolls off back of side shelf thru a 1" gap between shelf and side of seat. I found several "lost" scupper plugs in there!
I agree with you on the weight distribution issue. I used to just keep an ice chest or tool box on port side to keep it balanced until I installed the galley seat.
The SS thru hull is the overflow for the baitwell; the original inlet/outlet was covered up by the flotation tank on the bracket. I don't have a pump! I kept the original Moesly concept which circulates water pretty well as long as you're moving. The 3/8 pvc tube in following pic is cut off at 45 degrees at the bottom. When I want to use the bait well, I just pull the plug from the overflow and shove the pvc tube down about an inch so it extends below bottom of hull. Puts out a pretty good stream of water when you're on plane.
Next pic shows the water transfer tube up thru the bracket and into bait well. I also have a 12' length of 1/2" vinyl tubing that will fit over the water pickup. It makes a great deck washdown hose when I'm on plane!
For large amounts of live bait I'd need something like you have, but this rig is real simple and works fine for shrimp and small amounts of bait.