With a tri the biggest pain is a pitchpole. The problem is that the top of the mast is not parallel to the water but, without floatation, aimed to an angle under the water. An unsealed mast will simply begin to fill with water, becoming heavier and compounding the problem as the mast sinks to a lower angle. You're screwed at that point.

The only answer I could come up with on my tiny tri (after a pitchpole experience) was to stuff the hollow aluminum mast with foam noodles. I figured the expanding foam would turn to dust after a couple of summers. We then tossed the mast into my test tank (my swimming pool) and my wife and I could sit on the mast without it sinking.

Then, I re-sealed all the existing rivets on the mast with silicone. Not "Goop". Goop will turn to powder in a couple of seasons of Florida heat and sun. I also stuffed jumbo noodles into the beam (17' wide) and into the amas and also placed four of them as far forward as I could lash them down into the bow of the central hull. Next time, I hope the mast and beam will float higher which will give all my 150lbs a shot at righting it by hanging off the transom in typical grunt-and-pray capsizing/pitchpole fashion.

From experience on my small tri I believe the the CO2 idea is a super solution. I think I now have a use for those surplus CO2 inflatable PFD's that I have. I can place one in each ama bow with a cable attached to the ripcord on the CO2 bottle. I have to figure a way to keep them attached to the ends of the bows once they're inflated.