I don't dispute a single point you made. That being said, I believe I can improve my chances of maybe getting lucky first by some rudimentary testing by mocking up a controlled suction panel for one side (1/2)of the roof, use two switchable fans, (so I can double the air flow over originally considered to judge that effect) fabricate a full height (24"?) wool tuff vertical tree near the rear location of intended wing, rig up my Go pro for documentation, and make some 80mph runs to see if indeed I can vary the air stream, how much I can vary it, and where the laminar and turbulent interact at that location. All hopefully for less than a $1000 bucks. I probably would first need to spend some time optimizing my suction test mock-up panel, in regard to number of holes, spacing, diameter, angle etc, before I move to the tree wool tuff testing. I'm retired, I got time God willing, but money always runs out at some point.
Even if the suction trick completely fails, I'll have a better understanding of the useful location for wing mounting height in the end I believe,