If you use a drop-away rest, don't worry about waterproofing them.
Why would that matter at all?
I used to use that silicone powder that you put in the ziplock back and stick the feathered end of the arrow in and work it in real good. The bottle felt like it was empty.. but it was full of this stuff. I was sold when the demo guy dipped the feathers in a fish aquarium and pulled it out and it was completely dry.
Don't be folled by tests like that. After waterproofing some of my clothing, I can do the same and even run it under a running faucet for a long period and it will come out completely dry. But put the same material in a continued rain, or even mist and it will get wet.
Thanks for the suggestions. I will try some of them.