I tell you I have thought of this for years trying to get that in deck livewell to work properly. I think I even posted the same theory as you, but the best I solution I came up with was to cut the whole livewell out and use a 30 gal barrel that is completely free flowing and drains overboard. A few years back I was 15 miles offshore and took on ALOT of water for various little reasons that added up to a big problem. It was so much water that I could not get the boat on plane and my bilge pump quit. I realized at that moment that I had no access to the bilge from inside the boat. I couldn't bail if I wanted to. I decided when I got home to cut the livewell out completely. I reshaped the hole in the deck to fit a watertight Armstrong hatch and glassed over the drain hole in the transom. Before I had to go thru the hatch in the splashwell to access the bilge. Now I can reach the seacocks, bilge pumps, and bail (if ever necesssary) from inde the boat. I don't use a livewell that often so to me this the better solution. I'm thinking now about constructing an in deck insulated fishbox where the livewell used to be.
