sulphur, I'm in the same area as you (only an hour away from your location) and I know what you mean about humidity. I work with hickory mostly and I try to play it safe with it. What I mean is I give the stave as long as possible to dry but then when I'm ready to work with a piece, I store it indoors all the time. I work with it outdoors, but then as soon as my day is done with it, I bring it back into the more controlled environment in my house. That way, I don't give it adequate time to change much to the high humidity outdoors. When it is a finished bow, it will be stained and sealed (usually with poly) and stored in the house anyway, so I treat it that way during the tillering process.
I don't know if this is sound science, but it seems to work for me as most of my bows have taken less than 3" or usually 2" of set.
-Prof