[aerohead]

I suppose the idea is to get as much flow support surface without aggravating frontal area back there,so that said,it would point toward the green line version.
Renault,and one of their VESTA concept cars comes to mind as one car which had the abbreviated skirts with a raked bottom edge.
I ended up with this on the truck,going from a full-coverage skirt,back to a partial-coverage skirt.And then I altered the rocker panels fore and aft,to pick up where the skirt left off. This way,I wasn't adding frontal area.And the truck is indicating it's highest ever mileage,so I don't think it hurts too much.