@Andrew *********
Since you passed 50 years, you could apply for a Non O-A one year visa which gives you up to two years almost continuous stay in Thailand. You’ll need to re-enter one time close to the one year expiration date. Then you’ll just need to show proof of funds in your bank at home.
You can also apply for a 90 days regular Non O and do yearly extension of stay without leaving Thailand. You’ll just need to put 800K thb in a Thai bank, but the money is still yours and the fee for this visa is just around 150 usd (in Norway) and yearly extension of stay in Thailand is 1900 thai baht.