Asking on behalf of someone else: A friend arrived on a 30-day visa exemption, then extended it for another 30 days. He made a mistake booking his ticket out of Thailand, so in total he'll be in the country for 61 days, not 60 as legally allowed.
He knows he can request an additional extension that will be denied, giving him an extra 7 days to leave. His question is: will that 7-day deadline be stamped anywhere on his passport, and will it cause him any problems if he wants to come back to Thailand?