You pretty much need the full MRZ or be lucky you get the right part (date of birth, document expiry and document number used) data at the bottom, it's unlikely you can brute force this in the fleeting time available with a run-by scan. If you have a digitised document number it is a lot easier but otherwise you need continuous access to the chip and when you have that you can also just read it.

See ICAO 9303 for details. (BAC specifically)