It's all about delta T, air flow, and moisture. A thermostat won't help if your existing one is working ...
1.) Are the carpets stone bone dry? If not, your cabin is already loaded with moisture.
2.) Is the radiator blocked? If not, do that with something you can monitor and alter like two cardboard box halves. Put them behind the A/C condenser. You do not want to overheat the A/C system ...
3.) Run it on mixed Defrost and floor heat if you have that option... The defrost will automatically engage the A/C to freeze the water out of the incoming air and the heater will do the rest. If the outside temps are below freezing, the outside air is dry already, so now you just have to manage the inside moisture.
4.) Re-circ air is OK as long as the cabin has dry floors. But, if there is any moisture present in the cabin, it will only make it worse as you are not drying anything out ...
5.) DO you wash your windows with soap and water regularly? You need spotless clean glass to minimize condensation. Dawn and water, wipe dry with terry towel. No haze allowed.