UPDATE: How I managed splitting the pdf

What I ended up doing was dropping each page of the PDF into an indesign file and printing that to a new PDF. I used half-pages forming full page spreads starting on page 2, and dropped in the PDF with import options checked, so I could do all pages. Then I just added pages and dropped images until I ran out of PDF pages, and manually moved each one so the text fell within separate pages. I deleted the extra bits at the beginning and end that were holdovers from other sections of the book and not part of the assigned reading, and I printed by pages rather than spreads, stretching to fill. Now I've got a 39 page doc that's going to be way less of a pain in the ass than the 20 page doc was.