I 'm glad to see you have finally had some time to do some CFD testing.
I'm actually curious if just extending the decklid and curving it downward would decrease your wake size. It would be easier to do and wouldn't be as big a headache. ( And it could be removable if you just bought another trunk and stored the original .
If you remember, your cars profile is almost identical to the Ford Fusion that ran at Bonneville. ( Which had a Cd of .20 while remaining rather stock looking )
Cool pictures ! I'm jealous.