The short answer is no. I'm not sure that I'd really want to, either. The rust business works both ways. If you put away a fly in a truly waterproof box, the hook will rust. I have several perforated fly boxes that hooks never rust in, even when wet. They have the additional advantage of sinking rather than floating away when I manage to drop them. Of course, that's not an advantage in deep water.
Things that I have tried include wearing a shorter vest, keeping flies that I care about in upper pockets, having water proof pockets on the lower pockets of my vest. None those work when I go for a swim, which happens all too often. I still end up having to find table space at home to dry out twenty or so boxes of flies.
I suppose carrying fewer flies (and keep them in an upper pockets is the real solution, but I also know that will never happen. Zip lock bags might be answer as well.
