it should be noted that although IDL and IDP’s are valid for 1 year after arrival in Thailand, after 3 months most comprehensive insurance policies are made void if you are still driving on a foreign licence. This actually voids the use of an IDP for longer than 90 days
YOU ARE WRONG it doesn't matter if you got the 1968 or the 1949 IDP: in Thailand you can use that IDP for 90 days, AFTER this you either need a Thai DL or you need to exit Thailand and re-enter, to start another 90 days
it's because in your home country, you cannot get 365-days multi entry Non-Imm-O family visa any more. Only the single entry 90 days Non-Imm-O visa type. Savannakhet is, together with Rangun (Myanmar) the LAST Thai consulate to issue multi-entry family visa. It isn't even mentioned on their website - you have to ask them when you visit them
if you are aiming for change from a visa-exempt entry to the 90-days Non-IMM- O retirement visa, click om number 9 for the requirements . . check here:
Graham, he wants to apply for the "change of visa type" from a visa exempt entry to a 90-days Non Imm O visa. A "30-days tourist extension" is not the correct approach .. . google "change of visa type Thai immigration" and you will find the answer