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Ha ha on the trunk! I'm an old guy and learned that one in 1978.
Never heard of the Karman Vortex Street problem.
Rocker 59, that is how it feels, a left right buffeting.
Something as simple as adding a couple of Vetter pop vents to the screen may work. Or, you may have to lose the large windscreen.
Not sure what "updraft" feels like, so I don't know.