Having taken a look at Nicholas Sceaux's terrific opera scores, I found his pageBreakHack function. This function inserts an empty score with \header {breakbefore = ##t} into the music, forcing a pagebreak at that point. It looks like this:
seeing that the Devnull context discards all it's contents. But the effect is that it creates an empty page and then puts everything on top of each other at the next page. Is this a bug, or am I missing the point of Devnull?
Now I am trying to find the correct properties to tweak to ge the inserted score from the original code to take up zero vertical space, but I haven't gotten it right yet. Any hints?