Machaca
The VS exists to prevent the a/c from getting out of shape, period. A Rudder isn't a necessity, as you know, which means the VS needn't be so equipped, and the shape in cross section does not create an airfoil. Technically, and I insist on it, an airfoil has an asymmetric cross section, not a symmetrical one. An a/c can fly with large razor blades for wings, airfoil isn't at all necessary. Examples abound, but I've started a discussion in Tech Log, rather than here, hope to see you,
bearfoil, friend of airfoilmod