Towing 6,500 pounds with a class C

I have the new Thor Omni XG32 Super C on the F550 chassis with the 6.7L Diesel and tow a 24ft trailer with 2 side by sides through the mountains of western Wyoming and Montana and have no issues with the 3k mile round trip and has more than enough power for the mountains, going up the steep grades it rarely down shifts and the engine braking is awesome coming down. Backing the trailer is not a problem either, the rear mounted camera comes in handy for backing.