How much bait do you need to carry?
IMO the best options would be:
1 Leaning post/ live well combo (This is what I'm doing on my 20 CCP rebuild)
2 Portable live well under an aluminum leaning post
3 Rebuild the transom to include a built in live well
4 You could also replace the coffin box with a live well, but the further forward you place it, the more your bait gets beat up.