I've self-published a few things with print-on-demand services (notably Lulu). Now, my partner has written and illustrated a children's picture book, and she's run into a notable stumbling block: each individual illustration (already complete) is intended to cover two full facing pages at once, across the fold. We have numerous picture books at home where this seems pretty standard. However: The print-on-demand services that we've looked at (for example, Lulu), all have a minimum blank gutter width, like 0.5" or so, which would unacceptably break up the artwork.
How can we self-publish a picture book when we need to print it full-bleed, and through the gutter (i.e., no white space in the gutter)?