I think people here forget that the new 5th wheels have much less wind resistance that the older models do with flatter face's ... If you look at the picture of the TT that TT has a flat face an I can see why a wind defector can help ...On my 5th wheel the face is curved both from top to bottom an on both sides this more arrow dynamic that a standard wind deflector ...
The other point about trucks having standard wind deflector on them, most over the road trucks the cab is built so you can walk around inside them, thus higher cabs an yes they defect the wind off the front of the trailer because the trailer have a flat face an grab wind not defect it ...
Safe Travels