Been working on mapping. Here's the poster map with a 24-mile grid over it.
I also worry that this scale is somewhat too small. It's only one or two 24-mile hexes from Ghostgate to Dagoth Ur. From one end of the map to another, Vivec to Dagon Fel by boat, it's only five or six days under sail in a swift ship (not allowing sailing at night, as the coast is rocky and treacherous). Under two weeks to circumnavigate the whole island, even in a slower sailing vessel and without sailing at night.
Here's another with overlays for population density. Yellow hex overlay indicates taxable borderlands (~100 families per 6-mile hex; excludes the untaxed and illegible Ashlanders), green overlay indicates civilized population density (~250 families per 6-mile hex), and blue overlay indicates double-civilized population density (~500 families per 6-mile hex).
I think the total population comes up a few thousand families short of what I intended as of the first post; I think I could probably fit them into the blue hexes by raising population density there a little further.