The Thai side will not help you so much , Personally I use a broker to do it for me but it take few days as I need to provide everything to the broker via line and the broker send to my home address in Thailand and I pass the border in few minutes.
OK few things , Sadao is a messy border so busy and boring but easy to get your Malaysian insurance, Wang Prachan is great place to pass the border , nice twisty road. the insurance place is on the Thai side a small office on the right side before the check point
Have you been in the deep south? or just read stupid stuff on it, I am over there 5 times per year and never encountered any problems, maybe a good thing is more talking negatively about it and less foreigners so us we can enjoy 100 times more
You have more chance to die from a motorbike accident in Phuket than getting in trouble in the south, dont listen to the negative comments from people who never been in the deep south, Betong area is fantastic