“A muleskinner is a professional mule driver whose sole purpose was to keep the mules moving. The term ‘skinner’ is slang for someone who might ‘skin’ or outsmart a mule. Mules have a characteristic of being very stubborn so outsmarting them to make them move used skill, wit and a type of determination.”

https://arktimes.com/columns/words/2011/11/16/of-mules-and-men