Why not a triple tail, like the Lockheed Constellation, and the "Cardboard Connie", the Bellanca Cruisair/Cruisemaster?
Auxiliary fins were added to the 1937 Bellanca Cruisair because it would tend to go flat in a spin, and not recover by itself within the required six(?) turns. Some 40 years later, they found it could be predicted which planes would spin more readily by the intersection of the fuselage and aft area of the wing root. The more continuous the surface between wing roots, the more spinnable. It was evident on the Grumman Yankee/Traveler/Tiger of the 1970s.
GB