"4. Financial evidence: amount of no less than 500,000 THB OR equivalent amount in foreign currency e.g. bank statements OR sponsorship letter covering living expenses."
Nobody has ever made an extension on DTV yet, because the Visa ist just 102 days old. There are no official announcements from the Immigration yet, no known details, but you knows it for sure...? Okay... but I dare to doubt that...
P.S.: It's not even officialy considered as a "Tourist Visa"