Old West era story

I have trying to find a story that I read some time ago. The story starts out in either New York or Boston and the main character is a young man who sees an add for mail order brides and decided to try to trick the company with the help of a brothel of ladies who disguise him. On the train to his destination he meets an old lady and an orphan boy and is slowly changing into a girl but doesn't seem to realize she is female until she meets her husband and saves the boy from a hard life with the family who are only wanting him to do the work on the farm.

I thank you for your help with this.