Good question and smart thinking. I know no easy, guaranteed way to deal with this. My approach is to try to limit glue squeeze-out, particularly around the rod. You need enough glue to completely cover the surfaces to be bonded, but as little excess (squeezout) as possible. I would think that a small (very small) amount of glue near or even on the rod would not hinder function, while glue substantially filling the cavity or really bonding the rod to the neck would be a problem. Insufficient or excess glue was not a problem for me in the two headstocks I repaired, so I would be confident, but maybe I was just stupid lucky. Hope it goes well for you.