Well i finally got around to finishing a wiring diagram write up. This is abosultely everything you would need to make a dual controller. The relay in green is optional if you want to have a master OFF switch. Its also recomended that you have a master ON switch just incase something fails, you have a back up plan.
also i need to look up and figure out if the AC compressor is + switched or - switched.... but the wiring would just be one wire swapped on that relay.
-Patrick