Many of the boats I design are now being built with custom tuna tubes. They are basically a livewell with round tubes to put live albies and skipjacks into. The tubes are just big enough for the fish to slide into, and water fills the tubes inside and outside. The water is pumped in at a high rate and will fill the gills of the fish and keep them alive. These baits are already prerigged and attached to rods, tease up a bill fish and then throw one in. Would also be good for sharking but most guys who buy them fish marlin. These tubes are often put in a box similar to a transom kill box. I agree 2 is better then none, I'm just used to designing boats with 10-20 of them. If someone modded your boat to have them, make sure you have a very high speed pump, and I would recommend a back up as well to keep the fish alive. Also, each inlet to each tube should have a valve to turn the flow on and off, that way you only provide flow to the ones with bait in them. More flow is better, no need to hve flow going through unused tubes, they will just fill with the water being pumped in before it is drained from the whole box.
