Yes I had the same problem. What I did was stuffed a little neoprene pipe insulation between the pillar mounts and the pillar itself. That cut down on a lot of whistling.
The other thing is the whistling caused by the fins on the body of the light that dissipate heat. I had a lot of success by adjusting the light slightly upward from center. Use trial and error on that. The only time I get a little whistle is in a cross wind. Also check out this thread. This guy also has a good idea using stick on insulation.
Good luck 5 dollar 50" led light bar whistle fix