I was wondering if anyone knew/could make a version of the RobesMCBlack Hood with a shadow pane over the face area (just a black plain, basically)-- setting it to occupy the Head/Hair slot works partly for what I want, but leaves the interior of the hood open, making the character appear headless, rather than shadowy.

Thanks for any help

The hood mesh (by Madmole I believe) in http://www.tesnexus.com/downloads/file.php?id=24320 does that. You would just need to add a gradient (black to transparent I guess) to the appropriate part of the RobesMCBlack texture for the shadow part to work. Examine Slof's hoods in NifSkope to see how it's done.