I'm too lazy to sew one on, and just put one over my lifejacket. Only issue I've had (besides the occasional mainsheet slack hung up during a gybe) is the mouthpiece got hooked on something and pulled out of the tube, causing some loss of my drink. I've since routed it underneath to prevent this.

A large lycra rasher over all of this getup would probably do the same job, but I'd most likely look like the hunchback
of Notre Dame