I don't know if it's possible to totally prevent that type of damage. I've had success so far on my '38 by just driving slow when I'm on gravel. We put a rubberized undercoating on the underside of my fenders.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.