I didn't measure the stab as I didn't have time. Also, the fuse as a flat bottom, make it easy to stabilize for measurement. But I assumed that the bottom of the fuse is parallel with the zero line. Maybe it is not. If the flat bottom is slightly tilted up toward the tail, then the wing incidence would read a false high. If I get a chance in the next few days I'll take some more measurements. But I also wonder if picking the center line is somewhat arbitrary.