I guess this book exists after all:
I know a bunch of people who have been collecting Ultraverse stuff for years who had never seen one of these (I had heard that someone might have seen one, but without photo evidence I didn’t want to add it to the checklist). But you can see the evidence on this eBay auction. About $25 shipped.
I’ve already updated the checklist … now I have to keep an eye out to get one for my collection.