Leo,
Shouldn't the Schottky to GND be reversed compared to the diagram you uploaded?
My Splitboard diagram is messy, but if you don't mind, take a look. I can isolate the Splitboard and make it larger if that is necessary.
Air & Hyd Schematic with Splitboard
I changed the 1k resistor(s) that are routed to analog pins A0 & A1, to 10k, and shunt resistors to 120 (as you advised for Aref application). I'm going to change my code, and re-test on breadboard before soldering up these new splitboard layouts.