Get an OA visa, come and go as you wish for one year, second year just get a multiple reentry permit and you have up to 2 years of hassle free come and go. Then do it again. After that, do it again or settle in Thailand. Each entry is 1 year, so go out and come back the day before your actual visa expires and you are good to go for the second year.
It can be made into a 2 year visa by leaving a fews days before it expires and coming back to Thailand. Each entry is 1 year, but if you stay more than 3 months without leaving, you will need to do a 90 day report. Simple process. Explained multiple times before in this group.