Upper gap cover is in place. Can't really see out the back that well but I will be able to make out shapes during the day and lights at night.
Went on a 60 mile round trip and got an indicated 24.7mpg (23.7 mpg at the midway point) with the speed set to 65mph. I did notice that the back sides were flipping up a little...but overall the gap cover stayed in place. Not too sure how well it will handle cross winds.
The cover is currently 35" wide by 48" long. I'm thinking about cutting the length in half to 24" and adding a metal bar on the end to keep the sides from flipping up. I may eventually add in some side pieces. I'm not going to be able to install the side gap cover in time fer the trip. It happens...
I tried my first iteration with the aero cap hatch clips but found it cumbersome to install. I ended up screwing the bracket into the hatch main rails and initially bolted the gap cover in place since I didn't have any extra clips. A quick run into Lowes on the return leg resolved that issue. Installing/removing the gap cover now only takes about 10 seconds.