One of the advantages that a controlline flyer has is that he uses a castor based fuel and his flight is over when the last drop of fuel is consumed by the motor. That said we still use a good after run oil. I haven't seen a speck of rust in a motor of mine in at least 35 years. This is both C/L and R/C.
Make sure you run them dry and oil them well. Also correct about bagging them if off the plane, but immersion in a bucket of kerosene is still the best anti rust method known to us.
Dennis