TD,
I agree that the stab and rudder break off easily, but it isn't a Ringmaster S-1 if you move the stab down in the fuselage.
If your first one with the lowered stab was in 1955, that's after the OTS era had ended. Even a dated photo from 1955 would not qualify the model as OTS eligible. If it existed in 1952, and you had a dated photo showing it, I don't think there'd be an OTS judge or competitor anywhere who would object.
The change you made, sensible as it is for the durability of your model, is glaringly evident from just about any distance. There've been other (positive) suggestions throughout this thread for improving the ruggedness of the tailfeathers, without changing the Sterling S-1's general outline and configuration.
Actually, the S-1 is quite a decent flier, box-stock, considering it first came out 60 years ago. With dowel bracing (toothpicks?) and triangle stock under the stab, the tail pieces are much stronger. If you'd like to fly in an OTS Event, you could always try it that way. It will fly as well as your modified model.