I have priced out the alum. treadplate for a rock guard and my heart skipped a beat.

I have seen projects without rock guards and some with alum guards. Any advice, suggestions? Front wall would be two pieces of 1/8 luan thick with epoxy coating if I do not use the alum tread plate.
How well will the epoxy coating hold up to the road wear, etc? Should I lay a piece of fiberglass under the epoxy to add strength?
Thanks.