OK, I understand. So there would be two ways that I can think of to achieve this setup.
You would need:
3 wires for the sensor array (6 if using the SD card slot)
3 for the Digitiser (4 if you need to dim the display via OE).
2 for Vcc and GND
So that’s 8 wires (minimum) between the two racks. You could use thin gauge wire for the data lines and something a bit thicker for power and ground. This might fit inside some paracord sheathing, which would make it look pretty nice. You may need to experiment with different size wires and cords to get things to fit.
You would need:
An extra Motherboard connected to the underside of the right-hand rack. This would be powered by a separate USB cable. You can have these working independently with separate code for each (a lot easier to code), or you could link them via Bluetooth by installing a BT module for each.
The paracord idea could be cool as paracord comes in thousands of colours. It would be pretty easy to do and fairly cheap as well.
There is one small problem, the Motherboard is designed to go on the bottom of the rack. As this is where the gap for the USB is positioned on the side panels. You could wire your own USB or 5V power straight into the terminal blocks, so you don’t need the USB socket. This can be done with an old USB cable by chopping off the end and plugging the black into the GND terminal and the red wire into the Vcc terminal. You could also redesign the rack and print it yourself. Or you could ask me to make some modifications to fit the bill (when I have more time).