Hi Dradus.
That list is a good start for optimizing your EV.
As for the rear spoiler, have a look
here and
here (starting @ post #78) for examples of partial "Kammbacks" for hatchback type cars.
As for VG's, I've yet to see any evidence that they help in any way at the trailing edge of a bluff body (like a van/hatchback). We know they work on wings, and at the roof/rear window transition on some 3-box sedan configurations.
Anyway, looking forward to reading about your project.