Since I had inadvertently deleted my original circuits.io project and needed to spin a new board anyway, I shrunk it down to a 0.4x0.5" board. I had to rearrange the SJ pins some to route everything, so it's now got the following pinout:

Note that pins 11 and 4 are tied to neighboring pins due to the proximity of their vias. That shouldn't cause any issues during programming... I hope. Once programmed, those pins are not used, so have high impedance and should be fine.

This layout, once again, ensures that the DIn connector and the five floating SJ pads can be used to program the CMIC after it's soldered to the board (but before any jumpers are closed).

These boards are tiny, and a set of three costs only $1 from OSHPark. I'm considering an entry in the square-inch contest, if nothing else to get more visibility for it. Unfortunately, I can only export gerbers from circuits.io, not .sch/.brd files, so I'd have to fire up something like KiCAD and spin yet another version for them... At least I manually edited the silkscreen layers before uploading to OSHPark so they're not so cluttered.

https://123d.circuits.io/circuits/1188853-tiny-ws2812b-delay-splitter

https://oshpark.com/shared_projects/NWQyRSNJ