Thank you both...

Bax, dihedral was my first option, I was confused by our expert guy at the field. Make sense. I fly both Cessna's and Piper's, and the effect is not as dramatic as in my model, though...

Mesae, perhaps I miss constructed the question. What I meant was: Is there some (empirical) information about what would happen if I reduce tail moments, generally speaking?
I have seen this kind of information in other subjects, such props, engines, areas, etc. , so I wonder something like this already exists in moments... I don't think I would have enough time to become an aeronautical engineer, and I definitely will test in known designs, as I am doing today. I just wonder if someone else did the first steps.
Probably I should post a new topic...

Thanks again