Ok, I didn't take the page layout into account. Putting three fragments now on each square page, going back to 18 base fragments or 6 pages, which is nice because originally everything was based on ternary counting. To get the edges, I'm going away from complete graph, but each vertex has 12 edges.
Here's how the edge set goes: https://gist.github.com/Sciss/3a243b11ea0302f97cfb824ea1ff9f21