Man I can feel your frustration. Your normal set up looks good to me no pucker. The interesting thing is you said that an inward movement of the aperture corners resulted in a pucker. That’s not what I get. I think your inward movement is a forward one not an inward one. I would hazard a guess that’s the problem. All I can suggest is try to move your aperture corners inwards without your lips looking much different ie not moving forward. Maybe your feeling of an inward movement is actually a forward one. Does that make any sense ?