the current thinking is that none of this stuff does much good.
Here in the midwest we get scattered thunderstorms virtually every afternoon during parts of the summer, so I have done a ton of reading on this topic while trying to find a way to stay out on the lake while they blew through.
The short answer is as Jeff said above, nothing you can add on really makes a difference. Get off the water if you can, cringe and hope for the best if you can't. The good news is that serious injury or death is surprisingly uncommon, considering how relatively often sailboats do get hit. The bad news is that serious structural damage is extremely likely.