To deflect wind from hitting the top bar? If so, you won’t gain any noticeable difference in road noise or range. Deflectors are for large racks that make a lot of noise and catch a lot of wind. If for something else, what might that be?
Shot in the dark here but I believe Yakima makes our crossbars.
Perhaps this would work? https://a.co/d/9om6Mt8
Thule makes one too https://a.co/d/2BWJlHE
And others https://a.co/d/4UVuzsH
Like @ABILISK I don’t entirely understand the context and purpose but that’s my best guess as to what you’re looking for.
I ordered the GoSun EV solar charger, so trying to prevent the thing from turning into a giant wing and ripping itself off the crossbars due to the angle of the roof.