additional progression from SPL SE2 to SE3?

I'm looking for suggestions for an additional progression to help transition from advanced frog stand to tuck PL. Like many, I've mastered SE2 but am stonewalled trying to get hips to shoulder height in the tuck PL. I've used assistance bands in the past four extended periods and found when I removed the band after several micro cycles of increasing volume there was virtually zero progress in my unassisted tuck PL. Any tips would be appreciated. Yesterday I did two sets of 60 seconds sPL SE2 just to make sure that was solid and also did some PL leans to make sure my hands were in line with my hips. All seemed good there, I'm just wondering if I'm missing something. I was thinking about performing the tuck PL with my knees pressing outward against my inner elbows as a form of assistance, as that seemed harder than the standard adv frog stand where one's knees are resting on the elbows. Good idea, bad idea?

As an aside, I haven't skipped any exercises or mobility elements.

How are you attempting to enter the tuck planche? Can you post a video of some attempts?

Were you making sure to protract in the frog stand progressions?

I'm attempting to enter the tuck PL just as the athlete for in the video. I squat down, elbows between my knees, protract and depress my scapula hard (though perhaps I'm not 100% sure on what the "scapular depression" should feel like), and lean forward. I seem to lose some of the rounded back, so I'm assuming I'm losing some of my protraction and my hips sink. My feet are at that point elevated maybe 3 or 4 inches off the ground.

I've never posted a video before, I'm assuming it needs to be embedded from a third party video host. I'll try to figure that out and see if I can get a video up.

You can just post a youtube link, and I think it will automagically embed the video.  

Killroy, are you feeling a strong pec activation in your tuck planche? It took me some time to get this going and it has contributed to getting my hips at shoulder height.

Not always, and honestly I haven't really prioritized that as a focal point when leaning into position. I'll see in tomorrow's workout if by really working to activate my pecs if that helps with hip height. Thanks for the suggestion.

ExRX.net- Articulations: Scapula depression