If you are talking about that big "billboard" that hangs down across the back of your coach, there are many threads that discuss the pros and cons of these things, and the split is about 50-50.
Mine never had one so to protect the toad, I added some length to the 4 wheels mud flaps and a hula skirt type flap across the back like so.
Been very pleased with the results, and the cost was very little.
Mike in Colorado
2004 Fleetwood Pace Arrow 37c, 8.1 gasser, (Jezebel) Ultra RV ECM / TCM, plugs wires, and rear track bar, PPE deep Tx pan, Bilstein's, Sailun's & Sumo's all round, pushed by a 2002 Grand Caravan, on a Master Tow Dolly.