This is very frustrating. I already posted this, and somebody came up with a nice solution from Appleton. Unfortunately, the post seems to have been deleted.

I need to install a CS6369 recep in an interior wall of a building containing many small medical offices. For the times when the unit will not be plugged in, I want the recep to be covered. Unfortunately, the covers are designed to fit on an FS/FD box. My plan was to install a deep 4S box and a single gang mud ring. I'm not sure if anybody makes a single gang mud ring with the four corner screws like on a FS/FD box. I believe the only cover Hubbell makes for the CS6369 is the HBL7774WO or HBL77CM74WO . I wasn't sure how to attach this cover to a single gang mud ring, but somebody recommended Appleton FSK-SBA adapter.

Can anybody else think of any other solutions?