Have there been any real-life castaways?

[Jeeebus]

I'd make sure to take the GPS and Sat phone with me. I'd even buy two of each and keep the others in a salt water prof bag in a Go backpack.

the best laid plans tend to disappear when your boat suddenly catches on fire or capsizes from a surprise wave. Unless you have those things on you at the time, there's a pretty good chance they are going down with your boat.