Wouldn't an integral Bill of Rights have likely contained all 12 of Madison's originals, rather than the 10 that passed? So, them plus the 27th plus the failed proposed one on the size of Congressional districts?
Article the First and the XXVIIth Amendment were included in Madison's proposal because like the Bill of Rights, one or more of the State conventions that ratified the Constitution had recommended them. His proposal was therefore not something that originated from him ab initio, but a cobbling together of the various proposals made by State conventions. Without a Bill of Rights to be attached to, I'm doubtful that the First Congress would have sent them to the States.