For some reason this website didn't notify that you had posted another message.I just found your reply.Sorry it has taken so long to connect.
I am also working on this mystery.I have a copy of Sarah's book and have also been corresponding with a descendant of Wilson's for some time.William is the piece of the puzzle I'm focused on. In a previous posting you mention that you are a descendant of the William who came to Iowa with Wilson on his trip from Indiana. This is very exciting, because it may help to answer both your question and mine.Do you know the name of William's wife? The names of any of his children (other than Bryant)?His siblings?
I am a direct descendant of William Irvin Brewer of Indiana, who was Wilson's nephew, and who had a son named Bryant in Iowa around the time Sarah mentions.However, I am still looking for more clues to support (or disprove) whether my William was the "Little Bill" mentioned in Sarah's book.
Please feel free to contact me directly at my AOL address.