You bring up a good point. I don't wear a vest. I carry a map case. Okay, it's a man purse. However, it is waterproof. When I figure on rain, I take out all my good wooden calls and use calls things like slate and glass pots and lucite and plastic strikers. If it is going to be really raining, I may just take mouth calls.
The past few years, if it is really going to pour down I head for one of my luxury deer shacks.
My shotgun is all painted in Krylon, so it holds up really well in rain.