How challenging is it to extend a DTV visa in Thailand, and what documentation is required?

Extending the DTV visa in Thailand can be quite challenging, with many users reporting that immigration officials often prefer visa holders to leave the country and re-enter instead of granting extensions. While it is possible to extend the visa, especially in places like Bangkok or Udon Thani, applicants may encounter difficulties and need to provide specific original documents. Users have shared mixed experiences with extensions, suggesting that it may be easier to do a 'border bounce' rather than pursuing an in-country extension. Additionally, discussions about tax residency indicate that total days spent in Thailand, rather than consecutive days, determine tax obligations.