A large part of implementing a "leading plate" would be holding it in place. I
think it would take more than just a pole. It would probably require an A-
frame at top and bottom. The low point connection wouldn't seem to be a big
problem. But the upper point of connection with the body work would be
around the top of the windshield.
Maybe the leading plate wouldn't have to extend vertically the full height of
the car. Perhaps just part way up, say to the belt line/bottom of the
windshield.
[Edit:
There is always the possibility that turning the plate on its side, so it was
horizontal, might work too. I think it would be easier to implement at any
rate.]
Who knows? Not me for sure.
I think I meant to say that aero mods should first be made at the front.
Yes, for the typical car. (But not for a car with a boat tail.) If this worked,
perhaps there would be little need to work at the rear.
At this time this is an "idea experiment," and I'm not capable of mounting a rigorous defense of it.