[RolandF]

First photographs appear in "Wernfried Haberfellner/Walter Schroeder: Wiener Neustädter Flugzeugwerke - Entstehung, Aufbau und Niedergang eines Flugzeugwerkes", 3.Auflage 1999, p. 116, 117 and 124 with the caption "Entwicklungbüro Messerschmitt: Mustereinbauten"
No mention of any K-Variant.
WNF used to paint the last digits of the WNr on the fuselage sides. The 2nd, small, rectangle on the fuselage might be a work sheet protected by a transparent plastic foil with leather frame. Can be seen also on other production photos.
The tail unit was produced seperately by WNF in different production hangars and were already prepainted. As there are no wings attached it seems to be a fuselage unit taken directly from the production lines to test several new features.

Regards

Fran