Wear, don't carry, a marine non-self-inlating lifejacket. There's a huge variation in water survival time if fully clothed. Floating in a lifejacket, the water under your clothes will warm up. There's not much variation in drowning time.
I dinghy sailed in winter in Scotland, and capsized several times, with no wetsuit, and no problems. You might die after ditching, but you might not.