I'd do a 25 gallon Keep-A-Live round air infuser tank , I think it is the best thing out there , round makes a big difference , the water flows around the tank , it is quiet and doesn;t run your batteries down , can be strapped down to the deck and installed and removed from boat easily when needed , great product support from manufacturer , the bottom drain plug is a garden hose male fitting , you can get a Y on/off one to two adaptor and you could have a drain and a fill hook up easily plumbed , but I don't believe in water curculating from outside to inside the boat , shallow water and your are stirring up mud , idling and our put gas and oil sheens on the water and areas of different salinity are just a few of the times that can go wrong , but hooking it up that way would make it easy to fill up and do partial water changes

I have had many different livewells but the one that works the best is a floating minnow bucket. Put your bait in it and then place it in the existing livewell with some ice in the water while I travel to my TOP SECRET honeyhole that I am positive no one has ever fished but me, and then I set them out to float. Since doing this I have noticed that my loss of shrimp is perhaps fifteen or so to the quart. It's a little more trouble but it works super for me.

get a 94 qt. icechest go 2 homedepot in garden sec. buy a pump and 3/4 pipe an make a livewell!