This webpage has a photo that may be useful, it's not stated when it was taken but it's black & white so the assumption is that it dates from at least no earlier than the 1950s. There is also a second photo from the early 1940s (based on the uniforms being worn).
Both infer that the rear of the castle was at the time quite isolated from the nearby village.
http://www.philipcoppens.com/wewelsburg.html
P.S. Although in German, this website has many images including photos of the floorplan of the castle
http://www.cool-web.de/galerie/photo...urg/index2.htm