i run a gravel guard. 6000 miles of gravel road, so far, so good.
If I remember it correctly mine made it up to about 35,000 miles "so far so good". It was the next mile after that hurt. When I hit the rock that tore the original plastic guard off, I have to say that I didn't think that the impact was that hard. So what I'm getting at is those mounting bosses are very weak. Other than those mounting points you did a really nice fab.