Did any of your aunts receive a Civil War pension, Revolutionary War pension, etc.? Don't think it couldn't help you in your research. If the aunt tried to qualify for a pension, she would have had to have proven her marriage--that place alone could be a clue because if your ancestor's sister was living there, other family members could have been too.
And if the aunt couldn't find paper proof of her marriage, she might have had relatives provide affidavits testifying to the date and place of marriage and perhaps your ancestor made out one of those. Neat way to get information and an even neater way to get a signature.