I don't play either of those, yet, but the index-pinkie stretch I think you're talking about isn't too bad even with my small hands. I just stretch the pinkie out until hurts a little -- after a while everything loosens up and it feels great. Besides, I think it is always easier to stretch 'em out a little than to scrunch 'em together. You're right about the G chord. My fingers usually fall right into place.
Oh, it also helps to have a curly maple neck with it's numerous built-in position markers, especially when you move the bridge around.