As stated above, installation (on the hatch at least) is very easy even with the wheels still on. Only thing I had trouble with was a lot of dirt/small gravel up in the rear fender. When I went to pull the rear fender clips the sand jammed the pin making it impossible to pull them out by hand. I grabbed some pliers and pulled them out anyway without them breaking/stretching/etc. After being cleaned and reinstalled they're as solid as ever.
I have noticed that the rear flaps appear to sit slightly outward at the bottom, but I believe it's just the rear fender lines that make it appear this way. After looking at many photos in other threads, and even the RA video, they all give this appearance on the side, but you'll notice the bottom is level with the ground, so you're all set!