Newbiesailor,
So after you attach the life jacket and right the boat, do you then sail the rest of the day with a life jacket dangling from the top of your mast?

If you are not racing, why not just go with the low-cost method suggested of attaching a gallon plastic milk jug to the top of your sail? Spray-paint the INSIDE of the jug to match some color in your sail, and nobody will notice -- or else, if you are creative, it will become the "in" thing to do.

Swimming out to the end of your mast is potentially fraught with perils, which I will not go into here.