@Ton *****
your driver's license (if it's a thai license) still have your passport number on it though ;)
I used a hotel in Buengkan last summer (home provinse) using my drivers license at check-in.. Immigration gave grief about it when I reported back after a trip to krabi after new year. The IO looked very serious about me not reporting back after that hotel stay last summer, even though its same provinse. I did not get fined though as his superior told him to overlook it.
But morale is that even just using the DL they will know. And that in Buengkan even a registered stay in same provinse has to be reported on when back home. I will ask the missus to do the booking/check-in next time, and see if I can get away with not showing anything.