I haven't read any recent posts in regards to the subject of using foreign drivers licence in Thailand but as I can tell you that if your country is included in the UN treaty then as a tourist your are fine. Your insurance of any type will not be void which I can say because yesterday I had an accident at a roundabout in which a thai boy on a motorbike as all the other thai riders and drivers decided to go straight through as I was entering following the maked lane. So as a consequence he clipped the front left side which stuffed the guard and scratched some other parts. He wasn't going too fast luckily and had bugger all damage on his bike and body. The insurance man was called and the claim was done no problem but even though it was his fault to avoid going to the police station and paying 400 baht I had to accept a 50/50 fault lol. Which doesn't really matter that much as he will still pay the excess. So that is my very recent experience in regards to accident insurance in Thailand. If you are staying longer you need to get Thai licence as has been mentioned in another thread.