Dudeman have you seen the Korat Thailand 727 static line jumps? I’d have expected severe opening shocks but the videos show pretty gentle openings to my eye. The canopies “squid” which slows the opening. I think I’d have pulled off the stairs if I knew about those jumps. I do agree that an extended freefall at night with no clear horizon or azimuth reference and with an asymmetric external loaf would cause tumbling or at least a spin. Arching will normally stabilize you in pitch and roll but not yaw. You need a visual azimuth reference point to avoid a spin.
I have seen the Thailand jumps. I think they do get a pretty stiff opening shock. As the bag comes out of the container, and the canopy comes out of the bag and starts to inflate, that all does look pretty smooth. But the canopy goes out of frame before it's fully inflated. Just before/as the jumper goes out of frame, it looks to me like they are getting a pretty good yank at that point, as the canopy would be reaching full inflation. And that's with a bagged main. That unbagged reserve he jumped I think would open somewhat quicker. If it was diapered it might be a bit easier, but if it was just straight canopy with the line stows in the container, that thing would open like a bullwhip. Do you know which of those ways it would be packed? I think diaper is more likely, but the other way is possible?
(A diaper is a device that sequences the opening. It holds the bottom of the canopy closed, and the lines are stowed on it. When the chute gets to line stretch, the diaper opens and allows the canopy to inflate. The other way, the lines are stowed in the pack tray of the container, and the canopy is free to start inflating as soon as it leaves the container.)
As for pulling off the stairs - I think I noted this when you posted the video at DZ some time ago, but in the Thailand video, when the bag comes out of the container it immediately gets blown/sucked upwards to the tail. If Cooper was to pull off the stairs, that could result in the canopy entangling with the plane. Cooper in tow.
I don't buy that it would be so dark that Cooper 'couldn't see his hand in front of his face'. I've asked this before and not sure if I've gotten a definitive answer, but what was the moon that night? The pilots stated that they could see the glow of Portland lights. So with any ambient light, if Cooper could so much as see the clouds, he can see a heading. Whether or not he spins and tumbles would depend on whether he had any experience and how well he might naturally take to it. The money bag could certainly give him problems. My question would be whether it was centered and tight, or whether it was flopping around.
Also, apparently you're not going to confirm whether that was Taft you jumped at?