@Luit ****************
Reality is, at this time, there's NO indication of Thai Immigration requiring proof of your activity for which you received the DTV visa for, as of the original issue date, if you are leaving Thailand on or before the end of the 180 days and seeking to re-enter to get a NEW 180 day stamp.
YES, local Thai Immigration Officers are asking for ongoing proof of your DTV activity when you apply for the 180 day extension inside Thailand.
Will any of the requirements change?
It's anyone's Guess 😉