Hi MingJ,
let me tell you about one of our best kept secrets: 😉
The reason why we ask for glasses/contacts when creating a user profile isn’t so that we can track better. No, it’s a way to let people who e.g. sometimes wear glasses and sometimes wear contacts to set up different profiles and switch between them — and perhaps even more important: it’s a subtle hint to the users that you need different calibrations for different kinds of eyewear.
So if your game is to be used in a kiosk-like environment (if I understood that correctly?) then a plain guest calibration should work just fine. No need to worry about glasses.