Ok, so if I drop the LED monitoring support (Uptime) and monitor via IP then it would be possible to control 9x rigs using this device.
The NodeMCU supports 9x digital input pins D0-D8 so essential allowing 9 rigs to be controlled.
https://raw.githubusercontent.com/lvidarte/esp8266/master/nodemcu_pins.pngThese devices would be controlled over local wifi or remotely via nat/pat.
I may also develop a NodeRed RaspberryPi type controller to monitor and control a bunch of these devices from one web interface.
Naming
Monitoring
Auto Reboot (if your wifi is stable enough)
Grouping
Would be pretty easy to implement too