Does anyone have a source for getting a female stage pin and cover plate that will fit in a single gang box? Like a regular single-gang outlet except instead of 2 edison sockets, just the 1 stage pin.
Any manufacturer of power distribution products should either have this in stock or be able to custom punch some for you rather quickly. Immediately companies like Altman, SSRC and Union Connector come to mind.
Looks like Union Connector has the best options. They've really been pushing their custom manufacturing capabilities in the past few years so I'm sure they can work something out for you.