I just learned that apparently DAZ Studio has a built-in (?) tool for this, see video here: https://www.youtube.com/watch?v=YxE5Lfkid1M.

I haven't tried it or watched the video with full attention, so I'm not sure what the limitations are. But they do address overlapping UV islands by letting the user assign material zones to "templates" and then baking one image per template.

-- I'm not mad at you, just Westphalian.