RE: Engine Thrust Line
You might check the incidence of the tail plane and the wings on your plans. The full size planes use incidences instead of down and side thrust. My SE5a (Duncan Hutson design) uses this method and the plane flies very well.
For example: if the wings are +3 degrees and the stab is +3 degrees this effectively gives you 3 degrees of down thrust when the plane is flying level.