My fan clutch would cut in a start to roar at 207 degrees per my OBDII montior which I kept hooked up at all times. Since I traveled mostly in the Western mountains I was used to the temperatures rising but once the fan locked up things quickly got under control. If it was a long climb, the fan clutch would stay locked up but the temperature always stayed right around 207 degrees. As mentioned, keeping the RPM's up and slowing down on a long climb is the best way to control temps. Our coach was always loaded close to max and we always had a vehicle in tow.
You also need to make sure that your radiator cowl, as seen from underneath and behind the radiator, is sealed so that all air coming in to the front of the coach is directed through the radiator.
If you did not have overheating issues in the past than you have something that is correctable. You just have to find the exact issue and correct it. My coach would normally run all day at around 195(by my OBDII) no matter what the outside temperature was.