I was a bit demotivated after last weekend's windscreen disaster, so I didn't get much work done this week. Yesterday I redid the worst parts of the seam filler around that fairing, and finished the parts that I had not yet started. It went much better. The trick was to do it in small sections, so I could pull off the tape on the windscreen before the seam filler had skinned over. I will have a bit of touchup work to do once the new filler fully cures, but I am now confident that I can end up with at least a minimally acceptable transition from windscreen to fairing.
I screwed up trimming the piece of rubber inner tube that does the transition from the cowling to plenum chamber, so I had to make it again, for the fourth time. Grrr.