With unexpected extra energy, I decided to try shaping the headstock. That meant removing about 5/8" worth of wood. I used chisels, a rasp, and some sandpaper to arrive at this rough shape:
I aimed for 5/8" thickness where the tuners will be, and a bit of a... recurve? Bump? towards the center (convex profile) and towards the tip of the headstock. Surprisingly, it worked.
My goal is to make the corners and the overall geometric shape a bit sharper.
I'll leave it alone for now and move on to jointing the top and back soon.
Spanish cedar smells good, but the dust is nasty.