Under the current law, you only pay taxes on the money you bring to Thailand when you stay more than 180 days/calendar year.
Technically speaking this should be applied to most long term visas and you should pay taxes under other visas too (unless its a tax exempt visa) . But I think the Thai gov will enforced on the DTV more.
If you don't want to pay. just stay less than 6 months/year.
It works very well for a nomads who wants to travel multiple countries during the same year.
I too faced complications applying in Malaysia. Requirement kept changing on every follow up appointment. I gave up and applied in Hanoi instead. Received my visa in just 2 days.