Not saying this is what's happening for you, but a lot of times it is one or more of the mounting brackets, or that the rack is not loaded, or the way an item is loaded, that creates the wind noise. Sometimes it's just a matter of having all mounts tightened down to the same degree, or moving a rack back or forward a hair on your particular vehicle to avoid a harmonic vibration of sorts.
I had it happen with a roof rack on a passenger car one time near the beginning of a trip. We thought we had a wheel bearing going bad. Stopped at a repair shop, did a bunch of diagnosing, and finally found that it was the roof rack mounts just not tightened down evenly and that the difference produced a sound that transmitted down through the vehicle. That's all it was. After that, the whole trip of about 2,000 miles was sound free.
I have a Rhino Rack Pioneer Platform now and love it, and though it's on my trailer, I've never noticed any wind noise or vibration. One of the things I like about Rhino Racks over some others is that the slats go lengthwise, not across, and though some mfgs say it make no difference in noise or mpg, too many others know that it has on theirs.
Hope you get it figured out, and if you find a wind fairing that works or that it is from something else, let us know. Others may find the info useful.
.
