They came in a while ago. I figured out the double-sided surface mounting. Just flip them over and the parts don’t seem to fall off :).
One board, I cut the traces to enable it to act as the MCU in (source of the signal from the Arduino). This bypasses the local LEDs and just provides a signal to the serial chip. The idea here is that the Arduino and the first board can be remote to the first set of LEDs. That seems to work as expected.
The second board works – to a degree. The first LED comes on and works just as desired. Meaning the serial communication from the first board is also working as designed.
For the life of me, the second LED on the second board – not really working.
Could be connections – might be the layout – have hit a bit of a roadblock.
More updates when I’ve had some time to review the situation.