As an aernautical Engineer I'd like to answer the question posted by BOBFI: Stabs ususally goes aligned with wings or upper positions due to turbulences coming formt the trailing edge of the wing. If you want (or have to) put it in a lower position, you'd better GO low... this turbulence (named downwash; in the same manner than another geometrical property) causes "malfunctioning" of the stab: Vibration, local stalls; evetually stab doesn't works.
Hope my explanation is clear (I'm not natural english speaker)
Guille