indeed Lauterbach commanded in the Baltic Sea the auxiliairy vessel K = Kronprinz Wilhelm and attacked on may 27, 1916 two russion submarines the BARS and the GEPARD. BARS had no dammage while the two guns of the GEPARD were dammaged during the ramming.
On August 12, 1916 , the english submarine approached until 2400 meters the Kronprinz Wilhelm believing that it was a merchant vessel. Kronprinz Wilhelm attacked and thought having hit the sub, but E43 returned safe to England.
After the K, Lauterbach commanded the auxiliary vessel Moeve

There were some other ships used as U-Bootsfallen like the sailing vessels ANTJE and FRIEDENSBURG or the ALEXANDRA and PRIMULA as well as the ODER and the HERMANN.
But all in all the activity of those ship was very limited because there were at most 5 english and 3 russian u-boat in the Baltic and the merchant vessel were often organized in convoys and/or protected by swedish and german warships.