@Ron *******
I’ve seen feedbacks of people allowed to convert to Thai licence only with a national driving licence from an English speaking country.
We could convert only our Norwegian licence previously if we got a confirmed translation of our licenses from our embassy in Bangkok. The embassy has stopped providing this service, so now it’s no way around a IDP to convert.
I’m sure practice regarding this varies between DLT, but it’s wort a try to check this up.
For driving you’ll be fined without a IDP anyway.