I have stayed for 5 years on the METV (3 months abroad each year) until Covid started. However, as you correctly stated you need to be careful. In my first year, the immigration officer in BKK gave me a look like I am a serial killer. After my 1st year I entered AND left only via land borders (Nong Khai and Sungai Golock). There are plenty of more options to get your 60 days extension. I usually went to Phu Nam Ron.