When I was glider towing off a dirt strip over 40 years ago I was taught NEVER use more power power than is necessary to get the airplane moving. Sometimes just a brief rudder wiggle is all that's need to get it rolling with low power.
My experience with rock dings is that they are usually on the horizontal stab and caused by rocks being kicked up by the tires during landing roll out. Not caused by prop blast if power is managed correctly (minimum power for taxi and full power not applied until aircraft is rolling for takeoff)