As a kayaker, I just wanted to mention that many (most?) kayak fishermen do have 5-8 gallon livewells on their boats for bait and they're plenty big to store a few bass during the day. What I do when I fish CnR tourneys from my kayak is store the fish in a mesh bag hanging over the side while I'm fishing then put the bag with the fish in it in the livewell while I paddle. I have yet to kill a fish doing this for even a few hours.

TL,
Adam