Airfoil behind roll cage CFD analysis

Does an airfoil generate downforce when placed behind a roll cage? Since I'm starting to get along with the CFD analysis software I did some more simulations.

The airfoil is a NACA 2312 at 160 km/h with 20° angle of attack. Length ~170 cm, width ~20 cm. As I suck on 3d modelling, none of the models correspond much with the real world. Neither the results probably, but can give an hint of what you could expect.

Without roll cage

Scenario 1 - No roll cage, airfoil 40 cm above trunk
Airfoil downforce: 791 N
Airfoil drag: 282 N
Total downforce: 1810 N
Total drag: 1230 N

40 cm

Scenario 2 - Airfoil 40 cm above trunk
Airfoil downforce: 542 N
Airfoil drag: 174 N
Total downforce: 1482 N
Total drag: 1296 N

50 cm

Scenario 3 - Airfoil 50 cm above trunk
Airfoil downforce: 857 N
Airfoil drag: 268 N
Total downforce: 1742 N
Total drag: 1438 N

Scenario 4 - No airfoil
Total downforce: 738 N
Total drag: 1051 N

Conclusion:

A wide airfoil behind the roll cage does generate downforce, but raising it just a bit increase the effect dramatically. To no surprise, the outer parts of the wing are the most effective regions. Real world experiments are necessary to find the optimal location.