IN reference to the credit notation to "RED REED" below, I suspect that "Fitz" was a house-name at Gleason (like, "whatever fits...") but unless I'm reading the credits analysis wrong, I DON'T think Everett wrote these, if only because he had enough weight even in 1942 to have his flourishing signature on the splashes of both RED REED chapters he'd illustrated, and could easily have had the story credited to "By Bill Everett" if that were appropriate. Wolverton's proud posting of his own name on his intro of Scoop Scuttle bears this out, as do several other credits on the book.Gleason was magnanimous enough to credit his artists to a far greater extent than many other publishers at the time (even if Chas. Biro seemed to be signing everything whether he worked on it or not) and if Gleason were trying to secure ownership of a strip they thought had legs, (syndication still being the gold ring in those halcyon days) then it would be logical that a house name such as Fitz would get the byline. Further evidence by the sparse biographical info available about this vague presence in the Gleason shop.
Extensive searching for further bio on "Fitz" going back to Gleason's days at Eastern Color Printing, have turned up nothing, which further suggests the likelihood of it being a House Name.
Link to the book:
Silver Streak Comics 21