Put a text there: "This space intentionally left blank". Repeat until there is *no* blank space left.
Why do you feel this something to be "dealt with"? There are lots of books with (partially) blank pages. Not because the designer had no idea how to fill it, but just because there is no more text. A perfectly good reason.
Pick up any cookbook you have and look. Is *every* pages filled from top to bottom? If so, what did the designer do? Use larger leading on the text, fill up with colored shapes, or (re-)using a photograph or another image?
I believe in some of the older cookbooks hanging around our kitchen pages are always filled by allowing a recipe to begin immediately after the preceding entry and allowing them to break across columns and pages.
This is basically a design choice.
Thanks Jongware and Peter. I'll just live with some white area. I'm currently using small (hand-drawn) arrow graphics to divert the reader's eye, but so far, I'm not happy with the results. I'll plod along, taking your advice to heart. One of my concerns is being "too close" to the project to see things clearly and your experienced eyes help me.
Thank you both again for your input.
A good filler could be some random food-related clipart, perhaps. Don't try to fill up every nook and cranny, though, as it will get too busy very soon.