If you limit your visits to 90 days at a time you may be able to do it on Visa exemptions and extensions. Supposedly no restriction on how many times you enter by air each year.
If you plan to keep leaving Thailand there is no real need for a visa. Every time you return you will be given another visa exemption. 30 days at the moment but hopefully soon to be increased to 60 days.
Your host should do it. You may need a print out of it. I certainly did 2 years ago in Chiang Mai although in other offices I haven't needed it they have just checked online.
You could get 60 days but leaving Thailand, entering on a 30 day exemption and extending for 30 days. If you then still need the extra 30 you would need to leave again.
they really tried for me in Bangkok Bank. They speak good English but showed me the document, recently issued, that shows the type of Visa they can open an account on. Tourist is no longer one of them.