@oshpark were cool enough to put a call out for designs to be loaded on their trial run of a flexible PCB service. I applied and was accepted by the very helpful @Dan Sheadel. There's no guarantee that the boards will come back in a fit state to ship to me but here's a peek at what they might look like. The front and rear of the foot were split into two parts to improve nesting efficiency on the PCB "panel" - if you can use that term for flex PCBs: "sheet"? The images from the OSH Park online viewer aren't to scale, relative to each other, below.

Imagine the fabrication simplification of a developed device if this works!