Are the SSIDs in the network changing a lot? If you're seeing a lot of new SSIDs being configured, typically the best way to catch that would be through config audit report.
Otherwise, you could run the client session report and it'd show a pie chart for the SSIDs that have client sessions - when you use the 'Session Data by SSID' widget. Would need to isolate the portion of the network into either a group or folder for easier reporting (or from full list of all AP/Devices -> create a list view that filters down to the devices that you're trying to report on -> then use the pencil on the top right to perform a run report against devices from a custom view - this escapes the need for group/folder changes). Give it a try and let me know if it's close to what you're looking for.