I went from a 60 day tourist visa, to a medical visa, to a marriage visa. Not a problem if you meet all the requirements. This is my 7th year in Chiangmai on a marriage visa.
Actually you need 3 forms of income verification from your bank, if you are using monthly income (40k baht minimum) 1. Copy of the past 12 months of your passbook. 2. Income statement from your bank’s head office showing past 12 months account monthly deposits (100 baht fee). This took a week to get from Bangkok Bank. 3. A letter from your bank’s branch where you do business showing monthly deposits (200 baht fee).
My fear is that the minimums for the marriage visa will be boosted to that of the retirement visa (65k baht per month or 800k in a Thai bank, plus health insurance). I would still be in the clear, but not by much. My funds are transferred monthly from the U.S.
I would recommend a marriage visa to you. I have had one for two years now. Lower threshold to qualify, either 400k in a Thai bank or 40k per month income, with no health insurance requirement. The retirement visa threshold was raised earlier last year to 800k in the bank (400k after two months, I believe) or 65k monthly income, plus Thai health insurance. The insurance requirement has made it difficult for many longtime expats, causing many of them to relocate outside of Thailand. It’s good for one year, with reporting every 90 days (which now now can be done online).