I took down the latest version after doing some more thinking. My turn computations were too simplistic, and they don't have the explanatory value I first thought they did.
So I'm still stuck with an intractable problem. Everything from the right wing hit on through the sequence looks like a belly landing. I can't show good evidence that the high-angle bank was wrong, but it's incompatible with the rest of the sequence. I can show that a low-angle bank is reasonable, but can't give any hard evidence for it. If the plane came down with a high-angle bank, I have no clue how it could have transitioned to the belly landing.
More work to do.