To give my jon boat a cleaner look.  I am wanting to take the 100 qt. cooler that I use as a live well and cut it down, so I can deck it even with the bench seats.  What kind of total volume do I need to keep bass alive during tournaments, especially here in the summer in Georgia.

I guess, what I am asking for is minimum dimensions for a live well that may have 3 large bass and 2 smaller bass in it at the same time, since I fish Varner and other lakes in the area, where a 6-10 lb. bass is not out of the question.

Yes, it has an aerator installed in it, so there will be plenty of water circulation.

first you need to check the "rules" for the tournaments you are fishing. I Know BASS has a 10gal min livewell size, which is very small. The rule is enough water that a limit of fish can be safely transported in them.

I would make sure that the livewell is big enough. last thing you want is dead fish. Your 3 large and 2 small fish make me laugh & and seem confused :-?, what if you catch 5 big fish, now what do you do? or do you only catch 3 big ones and 2 small ones? and put back the other big ones