How to install an electrical box where there is no stud.
Carlon 1-Gang 17 cu. in. Shallow Old Work PVC Electrical Outlet Box B117RSWR - The Home Depot
Old Work Electrical Boxes How to install an electrical box into an existing wall or ceiling
Arlington DBHR131W-1 Low Profile IN BOX Electrical Box with Weatherproof Cover for Retrofit Siding Construction, 1/4-Inch or 5/16-Inch Lap, Horizontal, White - - Amazon.com
Retrofit 2 Gang Box, 20/CS ~ JXT Company
Retrofit 1 Gang Box, 25/CS ~ JXT Company
1-Gang 21 cu. in. EZ BOX Adjustable New Work and Retrofit Residen | Crescent Electric Supply Company
Arlington DBVR1C-1 Low Profile IN BOX Electrical Box with Weatherproof Cover for Flat Surface Retrofit Construction, 1-Gang, Vertical, Clear - Electrical Outlet Covers - Amazon.com
Retrofit Metal Electrical Box: Single Gang
Arlington DBHR1W-1 Low Profile IN BOX Electrical Box with Weatherproof Cover for Flat Surface Retrofit Construction, 1-Gang, Horizontal, White - - Amazon.com