I believe some immigration offices allow you to stay until the extension of stay expires. May give you some time to make plans and/or change the reason to being based on retirement. Best to check with your immigration office.
I'm no expert but reviews seem to say stay away from bio cam belts (timing chains are better anyway), oil pumps that drain quickly during an oil change and dual clutches. If these mechanical type of issues are important to you, speak to a good experienced mechanic as to whether any are applicable to vehicles in Thailand.
I am not sure what can or cannot be done in France, and I speak under correction here. I believe steps 1 and 2 can be done in Thailand and a further requirement is to obtain a Kor Ror 22.