Apply Non-o in home country. On arrival immediately open a Thai bank account and put 800k baht in after 2 months apply for 1 year extension and leave money in for another 3 months. Cannot go lower than 400 k and MUST be back to 800k 2 months before the day you apply for next extension NOT the day your previous extension finishes
You will enter on 30 day exempt. Then leave an buy a Non-o which is valid for 90 days. Then for your 1 year extension which can only be purchased in Thailand you will most definitely need 400k in your Thai bank account
You must have 40k paid into your bank account every month for 12 consecutive months on the day you apply for your extension and not on the date your previous extension finishes