Interesting thought, an autothrottle responding to aoa inputs. Can only imagine what type of human factors/mis inputs could lead to a recipe for disaster!!
I'm not convinced there is one aoa that can be maintained as weight decreases, to give maximum range. Assuming of course that pressure altitude/geometric altitude and temperature remain the same, with no wind.
While some may claim so, I've yet to see a convincing argument. Much like the "equal transit" theory of airflow over an airfoil.
My "feel" for aviation tells me that to attain maximum range, as weight decreases, one should also decrease aoa.
Hawk