Bucket, my feeble attempt at your pattern. I cant really get my shoulders anywheres close to steep, for me this is steep.
The more I trusted driving the right shoulder down the plane the better I hit it. There definitely is no attempt to use a swinging action here. I did hit it rather well.
As far as getting steeper shoulders ... it's hard to "capture" this in the pictures...but you actually "raise up" some in the backswing...you have the ability to steepen them shoulders out if you want...you know this stuff...change your knee flex (left bent right straight)...you REALLY need to "SAG" the left side...COLLAPSE it...you could feel like you are doing it so much that your head goes DOWN...
You have a nice swing....it's gotten much better...what do YOU see??? What do you see on the downstroke?