Your question was about the options when your boat was already sinking. So
the rest of your answers are fairly irrelevant, arent they?

oh god, no. unless one also asks the question of a young man, "What medication
scheme is the best in case you catch lung cancer 40 years from now?". Plainly,
not smoking is a cheaper, more viable option than chemo maybe at some future
point.

reducing the risk is always preferable. Liferaft or not, you already have a
greater chance of dying of skin cancer than drowning on a sinking sailboat.
For the price of the liferaft you can buy a LOT of sunscreen AND have a greater
chance of dying from a gunshot wound of a jealous husband at age 95 to boot.