Are you planning to overstay or are you in the midst of an overstay now? If currently not yet on overstay, it would be best for you to go to your local immigration office, pay the 1900 and get an extension. Unless you’re already on an extension.
I think you might be right, HOWEVER, if someone is deliberately trying to screw the immigration system, they should have the extra precaution handy. Thai immigration doesn’t do favors for people. Their function is to stop people from attempting to live here without proper documentation, trying to pass as tourists. A return ticket to my home country is more credible than a cheap ticket out on a low cost airline or a completely bogus airline ticket.