Steam guides tend to be far too long winded so ill keep it to the point.

By doing this you can gain an infinite amount of cash though the wagon fence by confusing it.

Step one: Find high value wagon
Step two: Bring it into the fence
Step three: Find another wagon of any value and bring it to the fence. (be quick or it will reset)
Step four: Sheamus will open both the doors and the previous wagon will still be there
Step five: You cant get the new wagon in so you instead get in the previous one which is in the barn
Step six: The game will think the previous wagon is a new one and will give you the cut scene
Step seven: Get in the new wagon and wait a second
Step eight: Sheamus opens the door again and low and behold the wagon is still there
Step nine: Repeat

Side note: If you chose the oil wagon as your high value first wagon you will gain 50 dollars each time. I am not sure which wagon is the highest value but im sure some friendly individual will leave that info in the comments.

Helps with bandit challenge*

If you enjoyed drop your lowest value steam reward and enjoy!