You should be able to set the AC as cold as it can be set and attach it to a Johnson/Ranco controller. The controller will then get it as cold as it can i believe. Otherwise you can set it to the temp you are looking for via the controller.
Yes, but this will only get to 60 which is the lower limit set on the internal AC controls.
The hurdle is apparently the sensor on the coils. I pulled that and stuck both sensors in the can. As long as I keep the coils from freezing it seems like it will get as cold as I want it to.
I've got the A/C plugged into a timer, so it only runs 15 minutes at a time to avoid icing the coils. I have no idea how much it is actually running, but it doesn't seem like much. The room is mid-50s at the floor, 60 at the ceiling. I'll see if I can take the whole room down to 50 but I don't think I need to go any lower.
This is my ghetto coolbot. A can to keep the sensors warm, a timer to keep the coils defrosted.