I don't have a rear panel yet and I thought the dust was bad. I took it out this afternoon and the dust was considerably worse.
I tried this near the back of the cab and it only pushed the air down to my chin area, moved it close to the windshield and I can feel it on my arms.
I still have about a 2" gap between the top and the top of this deflector. I think that if it is raised it will improve the airflow, but I need to figure out a different bracket, and get some sch40 pipe.