When my buddy goes to Mule Pulls, he takes a large horse trailer loaded with two Belgians and two Belgian size mules and a very fancy two row plow being towed behind the trailer. I have driven that rig. There is no backing up. When you pull into an area, you have to know how you are going to get out. When you do have to back up, you drop off the plow trailer to back up.
I have seen truck drivers back up double trailers but both trailers are the same size. That does make a difference.
By the way, the horses would pull the plow at a nice walking pace. The mules on the other hand would start out wanting to run pulling the plow and had to have a tight rein on them from going into a full out run while plowing. It took several rows to get the mules to walk while plowing. Amazing animals.
Jim Altmiller