I did know that, but didn't consider it all that important for CL, and made the mistake of designing a twin-fuselage thing (for a couple of Norvel 061s) that had smallish, low aspect-ratio tail fins. It flew great, up until the point where the inboard engine quit early for some reason. It was still flying very nicely, so I pulled it up into a wingover. About a 12 kt tailwind as it went over the top, speed dropped below Vmca, and all of a sudden the thing was in a flat spin, dropping straight towards me. Minimal damage, luckily. If I do another one I might rethink the tail surfaces.