I can guarantee you they are not going to say they will pull you out of the cab take you down an alley and flease as much bht out of you as possible. I've been living here awhile now and don't like the bastards they've made a few bht from me hahaha
Boy's in Brown. The police. You are talking about immigration guidelines. Thai police don't follow them not even there own guidelines. But like you said they odds are up there on getting pulled up.
You won't have a problem extending 30 day's they don't ask to see your plane ticket and no problem at the airport. The only problem is getting caught on the way to the airport.