Many changes last weekend. Firstly, got it going with the Ras Pi model 2 B. Dramatically faster than the older Pi 1 B, and also a much smaller form factor due to cabling. End result was a proper full wearable prototype. But resultant changes:

Gooseneck: I'd previously commented concerns about weight. Confirmed. Too heavy, it's gone.

Video: Still using the sunglasses personal display for the moment, but going off the idea. They are proving too restrictive. They need to be very close to the eyes, no more than about 1 inch, to work. Further out the geometry stops working. Without the gooseneck flexibility, they're proving quite difficult to work with. They're fine for a proof of concept but I don't think they'll cut it for a production unit. Probably looking at a 2.5in S-Video LCD instead. However, that leads into the next problem, for which I'll make a separate log.