Okay, one last question--I'm trying to get my flight timing worked out to HCMC. If my extension says "permitted to stay until 10 MAR 2019" is that inclusive of March 10th or does that mean I have to leave the country by March 9th?
TLDR : Answer Summary
The phrase "permitted to stay until 10 MAR 2019" generally means you can remain in Thailand until the end of that day, including March 10th. Thus, you can leave any time on March 10, 2019, before midnight.