Should I get a tourist visa in Bangkok or go to Poipet for an extension of my stay in Thailand?

An Indonesian traveler with a Visa on Arrival (VOA) expiring on December 19 seeks advice on extending their stay in Thailand for an additional 40 days. Comments indicate that the traveler actually entered on a 30-day visa exemption and options discussed include applying for a 30-day extension at an immigration office or exiting to re-enter for a new visa exemption. Additionally, it is noted that tourist visas cannot be obtained within Thailand and must be applied for at a Thai consulate in another country.