Mercedes has put "partial" rear wheel skirts like yours (minus your "doglegs") on all of its recent crop of efficient concept cars, from the Boxfish "Bionic" car to the Bluezero, to the F700.
All of which suggests if you can't do a full skirt, a partial one is still worth it.
Note that if you do a Google image search on the Mercs, their skirts may not immediately jump out because they often use clear plastic material. This pic shows one in
smoked plastic:
