^------What they said.
After you've used it a few times, you get used to seeing what it's supposed to look like right before it starts going in. In cases of changing conditions, or not able to get truck in same spot, you simply tweak the screw jacks to change the head tilt one way or the other.
Once you make contact with the stinger, your steering wheel should be straight. As you back in to the hensley, the head shouldn't move to either side. If it does, then you need to shift back over a touch. Having the steering wheel turned when hitching up makes it a lot harder to do.
I like the tool in the above photo.
