@Brandon ***********
Or, I believe that if you do not have that lump sum of 800,000 bhats in a Thai Bank (or do not wish to leave that in a Thai Bank) then you can show proof that you are receiving a pension of at least 65,000 bhats in a Thai bank each month!
On opening a bank account....some here have suggested using a Thai Visa agent to do that alone as they can do it quite quickly and stress-free....someone here had also mentioned that this will cost about 3-4000 bhats.