I live outside of Chiang Mai in Mae Wang but we have a second house in a Karin village at 1200 m. I can managed without air conditioning but not ideal. You need to get to about 1500 meters minimum. And most of the land at those altitudes are parks or occupied by hill tribes
Mine with AIS is set for only Thai use. So I don’t need to do that. However you can choose for data roaming in your package then when you travel to another country it should be turned off