[ghmerrill]

Is there a way to have this as two sets, with songs 1-16? I could just have two setlists, but that's a bit clunky, and also makes it tricky to move songs between sets (which often happens during planning).

This is actually an interesting question because it raises both conceptual and design/implementation questions about what a "set" is -- particularly within a software application that is basically oriented towards organizing a "library" of "collections" and what amount to (sometimes sequential) sub-collections.

Probably thoroughly thinking this through requires introducing something like the concept of a "performance" which would make more sense of temporal organization of pieces, possible repetition of the same piece at different times in the performance, multiple sets within the performance, etc.  Such a general concept of performance is really what's needed to model what you're talking about here (which in fact is a representation of a particular performance in terms of things that go beyond simply the content in terms of pieces and the sequence in which they're played).  Trying to stretch the simpler concept of setlist to model that won't ever be totally satisfactory.

Given that, I think the workaround you've settled on is probably among the best approaches.