do exactly what Chris says but you actually only need to get the OA visa in Canada and the day before it expires you leave Thailand and come back with another year Visa stamp on entry. Every time you enter throughout that first year you will get a one-year stamp.
There's no need to put any money in the bank in this first 2 years. If you want to travel after you get the last year long extension you can just go down and get a single or multiple reentry permit depending on your requirements.
When the two years are up there's plenty of options for staying longer and it's at this time you put the money in the bank if you want to stay. Actually you put the money in 2-3 months before your last stamp expires.
Then to change over to the long-term in country Visa, leave Thailand and come back after the final expiry date, you will get 30 days and as soon as you arrive go to immigration to change over to the non-o retirement Visa.
I used to do it 5 times a year. Every 10 weeks, it took me under 1 minute on my phone when I was on the throne. It's not rocket science. Username , password, passport number and nationality. Tick, tick scroll submit.