Best place for a good-sized livewell is amidships.

My v21 has a livewell as the base for the seat behind the captains seat. The base of the port seating is a fishbox. I am happy with this arrangement. The weight is as close to the center of gravity as possible and is balanced by the fishbox when full or crew members. It is also easy to access.

I don't think you want a large livewell in the stern for weight distribution reasons. I have my big motor, remote oil tank, kicker motor with bracket, 2 batteries with switch, and a 6 rod rod holder at my stern. That is enuff weight for the *** end.

Stinky, I don't remember what year your v20 is, but the older ones have drainage issues and low transoms. Put a big livewell in the back and you will make it worse. You will likely also need tabs to trim correctly when underway with the livewell full, if it is in the stern. If I had one of the older v20's I would put the livewell under the capt chair and another fuel tank under the port seating. Keep the livewell above the cockpit sole so you don't need a pump to drain it.