What I would like to do is utilize the sides of my Gamebook's text to show character artwork. As you can see in the picture above, the spaces tend to get a little big. My reasoning is that I want to display who is present in the scene without it intruding in the text itself - the scenes are already long enough without the artwork stretching the page!

Is there a reasonable way to do this?

A problem with game books is that they are pretty limited, so people who know how to do fancy stuff do not use them, which means there is not a lot of expert advice around.

Best I can do is point you to this guide to images for text adventures, and suggest you see if it works for a game book.
viewtopic.php?f=18&t=5566