At what hour would an a guest be considered overnight when there is a "no overnight guest of the opposite sex" clause in child custody papers?

I don't know if there is necessarily an hour component to such limitation in your child custody papers as much as it covers the intent and what the facts look like.  The intent of the limitation is to limit exposure to strangers for the minor children and potential harm as well as to limit the possible mental anguish or confusion that may come from having a parent dating and having someone spend the night when the children may not be of an age to understand.

You may wish to avoid such semantics and simply file a modification or clarification motion to clarify what the permissible parameters would be to allow you to have someone of the opposite sex in your home without unduly harming your child or children.