I've backed big single screw like tugs and ships. When backing, current, wind, prop will always put you to one side. The rudder is usually near useless. Since it is, I put the rudder over in the direction the stern is going anyway and depending on speed, go ahead every so often. Just enough to push the stern a little in the opposite direction, go astern and wait until it's time to go ahead again.
I've backed down narrow channels and around bends this way, many times.