Sounds like a great plan, let us know how it turns out.
Be sure to measure your PD outputs if you try to use multiple voltages from the same power bank.? My power banks wont switch one port to 9V/12V with a trigger cable, and simultaneously output 5V on the other port: as soon as I plug something into the USB-A port, the 12V triggered output switches down to 5V also.? I understand some power banks do support independent voltage output, but you need to find it in the specs.? Or just use your second power bank like I do.
Stan
