I could not find a picture, but I recall that Dusty Johnson had a real nice lightweight trailer with an aluminum stone shield, not unlike what you show here. Don't know if it was custom or all part of the trailer. I do know that Just down the road from you is a fireman who has a pretty good knack with sheet metal, particularly aluminum. Just sayin'. What I see here out of plastic looks pretty right to me. RAVE ON!!
PS, a good set of mudflaps on the tow vehicle will help also.