RE: Should wide,flat trailing edge be included in Chord?
Interesting question..
Considering that all-wing planes are less efficient relative to the same sized "normal" plane, not using some of the area to compute loading might make sense, IF we knew the percentage difference in effectiveness between an all-wing and the normal type.
We don't, so the wing loading is computed using all the planform area.
When the numbers are crunched, it's understood an all-wing will be less efficient.