Crab,
How far in advance would you have the customer book the flight....and the necessary training to use all that gear?
Surely you don”t think it fine to hand a passenger a PFD and Puff Bottle...as they head out the door to the aircraft do you?
And we are back to cold water shock.
Immersion suits and air bottles (STASS or equivalent) would at least have given them a fighting chance.
Even being shown a video of how to escape underwater would have better than nothing.
Planned flight over water out of auto range of land with water temp less than 5 degrees.........