Well I commend Creasey for all the hard work (which is what this takes), but I wasn't sure how "streamlined" that design actually is. 80mpg@80mph isn't too shabby, but an 850cc engine should be able to go a lot faster than 125mph even on a naked bike, but it is open in the middle which helps move high to low pressure, and it seems comfy. Looks are not a concern though, streamlining results are. If someone won't drive something safe and efficient because of how it looks, they are part of the problem.
Lets approximate the flat sided/ blunt nose design as a flat airfoil, as you can see the worst case is a 45 degree angle of attack (say 45 mph crosswind @ 45 mph). prior to 45 degrees (going faster than the crosswind) there is more lift than drag.
I don't know what you can permanently attach to a flat plate airfoil to make it stall sooner, stalling is what they do best, but it is making more and more lift (and gobs of drag) all the way up to 45 degrees.
edit: comparison to naca 0018
per
http://naca.central.cranfield.ac.uk/...report-647.pdf page 101 the cl increases much more dramatically up to 17 degrees (cl peak=1.3) then falls back towards looking like a sideways flat plate. it only has %30 more peak lift than the flat plate, but it comes on faster. The more streamlined, the more you have to deal w/crosswinds.
I'm leaning towards sharp leading edge/leading edge fence,splitter for a quick fix like sheepdog posted, but I am biased towards efficiency as being the reason for enclosing a motorcycle, since there are solutions for weather (and safety/not a helmet thread). But even then there are enough crosswinds in everyday driving that it will affect efficiency.