For singlehanding, why not attach a snap-type carabeaner to the mainsheet/traveler line with a short (1 meter) line to your trapeze harness?

This would seem to allow you to tack/gybe without too much hassle because the carabeaner would slide up and down the mainsheet.

An added benefit...you'd always have the mainsheet within reach.

If you fall off, your weight would begin to sheet the main in, most likely causing the boat to head up or flip.

Perhaps some quick-release mechanism on the short rope (or a knife) in case you're really getting dragged.

Also, maybe route the line to the upper back of your life jacket (don't sail without one ON YOU) so that if you are getting dragged, at least your head will be out of the water.

Think of your bailout drill when your parachute drags you over water....

For double handers, if it's really blowing the dogs off, everyone will be at the back of the bus anyway, so they could both clip into the mainsheet.