I have designed several scale models and since I am a chemical engineer, I don't (can't) get very deep into the aeronautical engineering. I have had a reasonable amount of success designing on a "don't do anything really stupid" basis. For a very serious competition scale model I suspect you will find that the thrust line and incidences match the full-scale plane. If they don't the outline deviations will be very obvious. I also suspect static judges look for these deviations. The planes I have designed on this basis have all flown. Not necessarily "on rails" like a pattern ship, but they met the requirements of scale flight.
Chuck