All right: the Calmo passage is "filled out," fitted with melodic foreground material, all the typographical concerns are addressed, and I've started to press on.
The 1999 beginning score lists 8'30 as the projected duration ... I could aim for that and claim it was where the music was headed all the while. As of today the piece is 4'20 done.
I'll go ahead and say it, though the future is always a bit of a mystery: if I write a minute more each day, the piece will be done by March.
So--we shall see.