Since the previous post, the first 2 flood boards have been built and used live at a concert (unexpectedly, but helpfully, allowing me to find where my protocol and approach has had some inherent weak points). To simplify, I shall just post an itemized list of the current state of things:

[VisualK-OS Control Center]
- Remodeled interior now uses a side-mounted AC port instead of a hardwired cord for the main power input to the system.
- Flood Bank Array controller/driver is mounted on top of its' PSU with a DB25 connection used to send the SPI control signals to the 2 shift registers in each flood bank board.

[Flood Bank Array (FBA)]
- Arduino driver sits inside control center, connecting to a small 3D-printed breakout box (carrying 5v+/12v+/SPI/GND signals) that currently has two RJ45 connections. Each RJ45 port sends 5v+/12v+/SPI/GND to each flood board with 3 pins allocated for current (GND) due to the relatively high amount of ~198 RGB strip segments per flood board. All transistors, resistors, capacitors and shift registers are located on a PCB mounted inside the flood board, to save from having to cram all the wiring into the already-crowded control center and run one cable to the stage to control both boards.

- Connected by RJ45, each board contains 4 RGB lamps and one board-wide set of white LED strips (5 addressable lamps total). The 2nd 74HC595 register's serial out pin is connected to one of the RJ45 pins to send the data back up the line and into the next port on the breakout module. Basically, the boards are one chain of multiple 74HC595s (as far as the Arduino is concerned).