Found a solution to my stealth problem. It's quite clever I think
Permanent mount is behind the toll tag. Technically you are not supposed to have metal within 4 inches of the RFID due to interference at UHF bands. But even if the reader fails to read my toll tag, the camera should capture my license plate, which will match my account in their database and the toll would be deducted correctly.
Detector installed. Stealth mode