I live in Alaska and have seen a million different rock guards on RV's of all types. A Bra is not the answer, fine silt and sand collect on the edges and rub the surface raw. A shield of some sort mounted out a little ways from the front will work, but will collect dirt which blocks headlights and affect engine/transmission cooling. For travel trailers, the best protection is Rock Guard flaps mounted to the truck hitch.
Personally, a clear bra film protecting the painted surface, headlights, and driving lights works great. They are practically invisible and do not cause engine/transmission cooling issues. For travel trailers, the entire front can be covered in clear film easily. I have the entire front of my truck covered and my rocker panels, works awesome.