Some of the things we have done...
Before you walk away, be sure to make certain she is standing squarely. Stack her if you like, but take the time to look where all four feet are. They should be square under the dog, each foot should not be moved forward or too far back. Press down on her shoulders and rump before you leave. We also used to gently nudge our dogs to make sure they were putting weight on all four feet.
Don't leave her just yet, but have the "judge" come exam while you are standing directly in front of her. Work up to more distance, a little at a time. Make sure when you tell her "stay" that you sound like you mean it. Don't be wimpy. Be prepared to verbally correct her if she turns her head toward the judge. You can also ask her to "watch" you if she is good at attention. Also practice walking all the way around her doing the exam yourself. Walk the six feet away and come back to heel, tell her to stay again and leave. It gets her used to seeing people coming from any angle. Have the judge walk around both of you, too. This is like any other stay and sometimes you just have to work up to it slowly, a little distance at a time. Even though this is a very short exercise, be sure she can stand comfortably for twice the time it takes to do the exercise ordinarily. Maybe 30 to 45 seconds. I have no idea how long it takes but it goes pretty quick. You could time it to find out.
We used to do a horrible exercise where we would stand a whole class of dogs in a line and the handlers would step away. Then the handlers moved one space to the right and examined the dog in front of them. Then they returned to their place 6 feet away from the dog they just touched, moved one space to the right and repeated until all the handlers had examined each and every dog. It was a really tough exercise, but had it's value. It was an awfully long time for the dogs to stand in one place though and one always moved, usually when the handler was down at the far end of the line. The person directly in front of the dog that broke, did a verbal correction and put the dog back in the stand/stay again.