yes with imagration, but it's up to your airline if you have not got a return flight, within you alocated visa term,I get non o visa based on marriage,
You know with extension leaving Thailand and returning obtaining another visa elsewhere or doing the 12 months extension, you can't prove to the airline when you coming back, all I was saying is for a tenner a onward ticket, solves the problem and hassle if you get it,
but the airline is required to fly you back to you country of departure, if imagration refused you entry based on not having proof of leaving Thailand within you permitted stay.