hm............now I am wondering if mine have a little more flex than needed, my first attempt was mounted at 1/2 - 3/4 inch and I had a rock get stuck on the thread and damage the lower part of the fender which is why I am at about 1 1/4" now.
yours look the same as mine, as far as having hardware on the inside, but I removed more glass from the back side. From the metal arms, I cut them straight to where the tread starts. I'll try and post a picture. Not sure if that's it. Give me a minute.