Have you looked into the spawn_conditions and spawn_events tables? I saw Kithicor "day shift" and "night shift" in there before, which was pretty cool - cuz I know what that means.
Whether this functionality exists in the EMU now, I do not know (is that Wiki fixed yet? /tap /tap /tap).
I can try messing around with that to get a better understanding, see if it works or not. But I think that would be a good way to go - mixing it with signal events in quest scripts to kick things off? I think you're onto something though.
(edit: Cavedude's database has the Kithicor example)