The following is based on unverified behind the scenes information and has not been confirmed by canon sources.
The Silver Shroud might be a reference to the 1936 fictional vigilante, The Green Hornet, as both of them are vigilantes clad in trench coats, use fire-weapons, have martial artist sidekicks and they are part of a multimedia franchise spawned from radio serials to live action TV programs.
Alternatively, the Silver Shroud could be a reference to the Batman: The Animated Series episode Beware the Gray Ghost, which features an old TV hero named The Gray Ghost, wearing similar outfit to the Silver Shroud.
The Silver Shroud may also be a reference to The Shadow, who debuted in 1930 on the radio program Detective Story Hour, and in The Shadow Magazine in 1931. The character later received his own radio program The Shadow in 1937 and appeared in film serials throughout the 1930s and 1940s.
End of information based on unverified behind the scenes information.