Outside of maybe a small light fairing on the roof to shroud the AC and vent equipment along with maybe some more aero mirrors, I'd focus all efforts on keeping the weight minimized. Many aero mods could just add weight. Your frontal area is such that you should resign yourself to slowest speeds and visit places instead of driving in strong headwind situations. You may be able to benefit more FE-wise by keeping the weight low for climbing hills. Besides, you aren't aero enough to take advantage of it on the other side.
