Here is a clipping (2 parts) about Dale Vern Maupin.
https://www.newspapers.com/clip/33375049/the_courier/
https://www.newspapers.com/clip/33375128/the_courier/
He was apparently picked up after 4 hours in the water by a Greek destroyer.
Fred Rochlin was picked up by an RAF Air Sea Rescue Craft according to his statement in the MACR. The way he worded it, it could have been a crash boat rather than a PBY or Walrus. It is not clear how long he was in the water.
Neither man ever "evaded" in Yugoslavia.
The book, "Old Man in a Baseball Cap" by Fred Rochlin is listed as a "fiction" book in this list:
https://fiction-books.netlify.com/