[Angel And The Wolf]

Yes, your #25 and Kach22i's #27 gave me the idea of isolating spillover between the air mass under the tail, and the air masses beside the tail. Then I thought, since the top view profile is a truncated triangle, (or a trapezoid,) and the side view is, as well, if I could wall off that area under the tail with an open ended 3 sided U section box that begins as a thin horizontal rectangular opening at the bumper, and transitions into a taller, narrower rectangular opening at the license plate end, maintaing an equal area for any cross section, I could eliminate the pressure drop, and thus the negative lift and the turbulence on the bottom of the tail, The sides of that box could confirm to the profile, and be a bit wider than the sides of the tail, so that if the skid pads hit the road, the lower box could slide up over the tail sides, perhaps with some sort of seal between the two pieces, and at full collapse would give the near 30 degree ramp angle of the car. (Drawing not to scale) Am I being more ambitious than it's worth?