You can make Damn near anything a baitwell as long as you take in some concideration to the weight. Remember, water is heavy, so if the compartment is suspended from the deck, is it to much weight? Plus, are the corners round or square? Square corners cause bait to get stuck and kill themselves.
Worst case you have to reinforce the compartment that you want to make a baitwell and round the edges inside. I also recomend painting/gelcoating your baitwell a greenish-blue color. Some people think that colors that resemble their natural habitat are better for bait and have a tendency to help the bait live longer and not get over stressed.