A work permit ties you to one employer. I know quite a few expats and many Filipinos performing in bars and clubs. They do not have work permits, but providing the venues are paying the required "fee" to the respective police station, there will be no spot checks
Why would anyone get upset? The DTV is available to everyone. I've created a business in Australia which I will "run" from Thailand. I'm set for five years. It's so easy