@Henry *******
your best option is the DTV, destination Thailand Visa, under the soft power category, for medical treatment. It is a five year visa giving you a 180 entry stamp each time you enter. You can leave and return in a matter of hours at any border and get another 180 entry, and do this for five years. Once you get this visa your wife can get a spouse visa under the same thing. The main requirement is having the equivalent of bt500,000 in a bank account in your name only, and medical treatment plan letter from your Thai doctor. If you came in on a medical treatment visa it is only good for the time you are treated, and then when you are released to fly the visa ends. It is not open ended.