A homemade wind tunnel like device constructed from a air compressor gun, outfitted with a string of yarn to show path the air flow. Plus a straight carbon fiber stick to show deflection.
Test on the wing (obviously)
Test on the tail (obviously)
Noted, this measurements are far from being perfectly accurate (though they were fun to produce), but they will serve as a base to tweak the model of desired plane's attitude compared to the angle of attack.