Generally a 3000w unit is needed. Some report with lower but that's usually at sea level on a cooler day. Go up or get hot and oops. Two 2000w combined is a safe bet and flexible but they will be louder than the 3000w unit while running the air.
The one consideration is if you are going up in altitude like I do, it takes a lot more generator than at sea level. Up there the popular inverter choices don't stand a chance and a 3500/4000 open frame is on the upper limits to do the job. I can run the converter or the air, not both.