Just a quick update. It’s not perfect by any means, but the best process so far:
Create the hair mesh by applying the modifer.
select the mesh and go into edit mode. select vertex to be able to select stuff.
select half the hair, and click ctrl+ until the full strands are selected.
Extrude X, Extrude Y (.0005 works for me)
Click ctrl+ 2 times to select all the hair you just extruded.
Ctrl I to invert selecting and work the other side.
The result is more geometry then you want really, but the hair is visible from nearly every angle
Anyway, recalculate normals, wait half an hour for a smart uv unwrap and that’s that. it’s not ideal at all (i’d like to control the exact UV of every strand by having it identical instead of unwrapping).
still, decent looking hair for ~159,000 tris is not bad.
Obviously this doesn’t help with curly or many other types where the extrude process will just fail or create a mess.