A really cool built-in design I've seen was in Charger Bass Boats. Of course, this could be in others, I haven't researched it in depth, they are the only ones I've seen it on. Anyway, they have these tubes, and I'm not sure if they are filled with some gas or liquid, but they run back and forth like refridgeration coils on the side of the livewell while also running along side the built in cooler. So, the ice you put in the cooler to keep your beverages/food/etc. cold, also transfer cold temps to your livewell via these "coiled" tubes. I thought that was a good selling point, that plus Chargers are good priced and I think are located here in Missouri...I like to ramble on, most of the time making no sense.
I know months ago I talked about my own livewell project in my old Tracker, well, to inform you guys, after 3 months, I'm almost done. Haven't had much time to actually do the work, been too busy keeping the new girlfriend happy. Anyway, don't hang me out to dry with my longwinded no sense post.
Mike