there are several Muay Thai gyms in Hua Hin, you need to find out which ones are government licensed, which you can book and pay, so they can supply you with the correct paperwork with which you can apply for a DTV. . DO YOUR HOMEWORK, buddy, ask around !
„Does anyone know any Muay Thai gyms in Hua Hin that’ll accept my DTV visa?“
WHY don’t you ask that question the correct way it should be asked?
A Muay Thai Gym does not "accept my DTV visa" . . you obviously have not aquired a DTV, yet. What the gym is doing is TOTALLY irrelevant.
They don’t have to accept a DTV visa. They are NOT the ones who need to accept.
Only a Royal Thai Embassy or Consulate must accept
***What you need is a Muay Thai Training Camp whose business license allows you to apply for the DTV on any Royal Thai Embassy outside of Thailand
So the only correct question is: ” is there any government licensed Muay Thai Camp in Hua Hin, whose paper documents over me joining a training seminar will allow me to apply for a DTV outside of Thailand”
if you knew the true scale of crashed business dreams of foreigners in Thailand, I guess you would want to take a beach or varanda chair and start gently rocking, and keep yer fingers off any businesses in Thailand