A friend made his out of vinyl contoured gutter with the back trimmed off and mounted upside down on the TC overhang with 3M automotive double sided adhesive. It was in a V shape from the middle of the overhang. It stayed on good with no screws. I don't remember all all the details.
I think he posted it on here a couple years ago, but I couldn't find it.
The difference it made was that it caught a lot of the bugs, keeping them from splattering the front wall in the truck bed. I don't remember how much clearance was above the cab.
I planned on copying his but never did it.
Maybe he'll read this post and put a picture on.