S. W. Erdnase was most likely a way for the author(s) to conceal his real identity so he would not be arrested, since Federal laws at the time prohibited the publication and distribution of "obscene" material.
[1] Genii Magazine devoted a large portion of its September 2011 issue to an exploration of Alexander's theory, providing substantial circumstantial evidence that links Sanders to Erdnase.
Chris Wasshuber has identified the printer and circus performer (door talker, Punch and Judy, magic) Edward Gallaway as an extraordinary good match for Erdnase.
Later Gallaway published other books in remarkable similar fashion (self-published, copyright registered, contact address given as place of work, and price printed on the title page).
Todd Karr has identified a Midwestern-based con artist and business swindler named E. S. Andrews who was active around the turn of the century and whose biography and range of known locations seems to fit Erdnase's.
During the 9th Congress of the Latin American Federation of Magic Societies (FLASOMA 2009) held in Peru, he explained the reasons and grounds for which the author of Erdnase has to be L'Homme Masqué.