Here's the detailed wire diagram I came up with. I've added a DPDT switch and a charge port. Also, I've powered the controller receiver directly from the DC-DC Step-Down Converter. I did this because I didn't want any of the SMC's to have to share power. I've also attached the Arduino code. I've removed the LED and debug lines to make the code as light as possible.
(PS. I had the wrong file attached for the wire diagram. Sorry)
(PS. I had the wrong file attached for the wire diagram. Sorry)