I would suggest trying a different approach to proving who your particular Reuben Bates was.
A Reuben Bates filed an affidavit for a pension for John Cosby who says he served in what he thinks was the 10 regt. VA militia of Louisa Co.,VA. Others listed by John Cosby as also serving were Thomas Denton, John H. Owen, Smith Hawkins, William Edmunds, John Cole and others.Can you tie your Reuben Bates to any of these people?
This affidavit was written in March of 1835 so of course your Reuben would have to still be alive then.