Did more laying out of the large-print edition--11 chapters down, eight to go. It may actually come in a little shorter than I thought, which is good. (Although it does mean that maybe I could have done it with 23-point line spacing. Oh well--I'm not laying it all out again now!)
Also I fiddled with the front and back covers (I can't do the spine until I know the exact page length). Because the text takes up so much more room, the large-print edition is a bigger book (7" x 10" instead of 5.25" x 8"), but apparently the proportions are close enough that I could just expand the cover art without making it look all distorted and weird. Whew!