I have been coming to Thailand since 1998 and owned a condo since I think 2007. Until 2015 or so I never heard of TM-30 or had any problem coming visa exempt near dozen times a year.
I have been using OA for several years. I contacted several provider 3 or 4 said NO. one said 2 months and at least $2500 The easiest way is to come to Thailand and get the med certificate for a few hundred baht from any hospital, or try and get it signed by a telemedicine doctor for $75 or so.