We have towed our Jeep several thousand miles, mostly paved roads but some back roads too, without any special protection, not a single chip or broken glass. Do your mud flaps drag and possibly cause the rocks to flip up? Its a long throw from the rear tires to the towed, especially from around the mud flaps. Or maybe it's just that Alaskan gravel road, I haven't experienced it and just don't know!
2011 Jayco Greyhawk 31DS with wife & 2 dogs
06 Jeep Grand Cherokee LTD