Just wanted to add my half cent here.
If you want to get a good result out of aero mods on your car, why not tuft test the (entire ) car to find the problem areas first ?
I would suspect that the main areas of drag are around those wheels ( and of course the rear ).
BTW You can easily add a professional looking 'trip-strip' to the rounded corners of the rear by using a piece of black electrical tape. It will be nearly invisible since the pillars are black themselves and the trim has the same matte black finish as the tape. A piece of small gauge wire under the tape would act as the tripper, and keep everything straight and pretty.
if you use a good quality tape it will last for years ( over two years on my car now ). Splurge and get the expensive type that is more rubbery and has less of a glossy plastic look to it - it's a few cents more
You can also use rubber edge moulding around the car to make skirts and such, and since it is made from rubber it will have a matte black factory finish and as a bonus, is entirely flexible. It's also inexpensive as well.
I'm worried that the flashing that you have used is not going to last too long without being all dinged up. It is also razor sharp, and I would hate to have a piece of it fly off and hit a pedestrian. Why not go with the rubber edge moulding instead ?
Nice car