Okay, revised texture overlay plan based on the uni-eye solution:

1) Body with hands and feet, neck and scalp.
2) Face with ears, inner mouth, teeth and tongue.
3) Eyeball (left and right sharing one map, mirrored).

4. Cornea (as above).
   5) Lashes (as above).

And possibly:
6) Floating brow mesh.

As for the brows, I have a shaped piece of geometry now, but should probably change that into a duplicate of part of the underlying face topology like on Apollo. Maybe for texture and mask painting it would be easiest if those polygons would just share texture coordinates with the ones below them rather than using a separate map?

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