While a rock guard will help with the smaller stuff like gravel, it will not prevent some things getting thrown up at your dingy. I once had a chunk of a truck tire blowout take out the left-hand front marker and turn signal light on my Jeep grand Cherokee 4' off the ground. It also left a 1/8" deep dent on the left front fender. If at all possible, you should try to avoid going over stuff laying on the road.
2018 Thor ACE 30.3
Towing 2020 Jeep Gladiator
Former 1996 28' Tiffin Allegro owner