I've found the best way to get back up a ladder in high waves is always feet first. If they can tie off a tag line to the ladder, float on the surface (fins on for fins on ladder or fins off for a fins off ladder) with your feet towards the ladder, pull yourself in with the tag line, and set your feet on the ladder rungs on a downswing and then quickly pull on the tagline to get yourself on the ladder. Once you're on, get a good grip as the upswing is about to begin, but at this point, your weight is on your feet standing on the rung, so it should be no big deal. It's a lot less consequential if the ladder comes down and hits your feet than if you go arms and head first to the ladder. I always use my feet first.
The nice thing about this method is that if you have your feet on the ladder while lying on the surface, you can wait for the right wave before pulling yourself up and on the ladder. And if you aren't able to pull yourself up in time, all that happens is you fall back and away from the ladder.