Please after 40 years with Cummins Ct. DO NOT use a piece of heater hose to extend the breather tube over time it will become soft and mushy from the oil. It will then kink from the air flow under the coach causing crankcase pressure to build up. This will cause the turbo to pass oil, low power, black smoke and poor fuel mileage. Most shop will just replace parts and not fix the cause. If you use a piece of hose be sure it is compatible with oil.
The dipstick may have been installed by the coach mfg and not calibrated. Ask your Cummins location for the proper amount for the PAN ONLY the put that amount in and remark your dipstick at that level. Overfilling will cause the rods to dip into the oil and cause many of the same problems.