I suspect from reading AA command recently that very few searchlight sites were of a permanent nature. Although the projector was supposed to be mounted in a shallow pit to offer the crew some protection against aircraft firing down the beam. And there were supposed to be a couple of Lewis guns in earth emplacements, neither structure would have left much of a trace. The most enduring structures would have been the bases for the accommodation and in some cases a pillbox. I'm sure site locations are recorded in the same documents researched by Colin Dobinson but since there are little or no remains and they aren't as interesting as Decoy sites it was deemed a waste of effort to document them in the same thorough manner lavished on Decoys and HAA sites.