I can't believe I forgot this one!
This issue of TwoMorrows' fine publication Back Issue! focused on "Weird Heroes", and included an article on The Phantom Stranger by Tom "The Comics Savant" Stewart. Here are two pages from it:
Stewart talked to Len Wein and Paul Levitz for the piece, adding their valuable insights. A fine article, well worth hunting down--you can buy it from TwoMorrows here!