I am very sensitive to cabin wind noise, regardless of what I drive, so it was an important considertation when I was test driving RVs. I have very little wind noise (less than my newer car), in the KS. And I am distinguishing body wind noise from leaky gasket or whatever, wind noise. My gaskets and seals are all good, so the only wind noise I get is a little off the front driver's side mirror (although I'm guessing if I sat in the passenge seat, I would hear some wind noise off the P/S mirror, also). Design features that I believe influence body wind noise include (you have already mentioned aerodynamic wind noise), dual pane glass, better insulated coach shell, mirror locations, a carefully sealed coach body, and amount and locations of exterior "noise" generators (i.e, antennas, cowlings, etc.) Any wind whistles from poor fit/finish around gaskets/seals, I can't address.
Coulter & Friends
2004 KSDP 3353/Cummins 5.9/Allison/Freightliner