[Christ]

Is there any info on the speeds at which the "pie plate on a stick" idea was successful?

I think, for all intents and purposes, this will be an exercise in futility at 60 MPH.

I'm saying this without experience in the field, because it's something I've never really gotten into too much, but I suspect that at the speeds that we're traveling, and even at 100 MPH, the object would still have to be ~60% of the vehicle's frontal area to have any notable effect. The lower the speed, the more of the vehicle's frontal area, and the closer to the vehicle, the object has to be to open a "pocket" of airflow.

What we're talking about here basically is cavitation, except without supersonic speeds being necessary.

If I had to chance a guess, I'd suggest that what's going to occur with this at our speeds, the airflow is going to begin to close behind the object, making it have to change direction more drastically to begin attached flow on the vehicle.

I guess the image that keeps flowing through my head right now is a truck "blocking" for a trailer... the cab's aero structure has to be larger than the trailer to maintain attached flow at highway speeds, so the flow tripping off the edges of the cab fairing doesn't begin to roll into the space between the structures.