I have been told by several of the oldtimers that there were Masked Marvels all over the country. They said the company picked very good regional players (so the travel costs were kept low) to put on the Masked Marvel show at rooms in their own and neighboring states. Danny D and others have told me that most of the stories of the really famous guys like Caras and Mosconi being Masked Marvels is just a fishermans tale.
I am not stating that I know any of the above as fact except that it is what I have been told by those who should have known themselves or knew others who did. So, some of it is based on third-generation story-passing and tales do change with each passing. However, I have never been given any evidence to the contrary and the stories I have heard are both consistent with one another and believable.