Here in Thailand weddings are meant to be fun. So you are allowed as much of a ceremony as you want or as little or in fact none at all. All you are required to be legally married is to go and sign the marriage contract at the local Amphur or registrar office.
To make the Marriage legal in Thailand is not the ceremony but the registry page or marriage certificate. No, religious ceremony counts legally as a marriage under Thai law except a proper Muslim Marriage as it is a legal document too.
Sadly, the Thai Foreign ministry does make it harder for westerners to marry in Thailand. This is in order not to offend the government of your nationalities.
Well, I believe that used to be the case. I believe they like the power it gives them. It is a district by district basis so some offices have more rules or ask for time to check things out. Which, I actually have never known of them actually doing anything but make people wait because they can.
So you must get their “written permission” in effect from your local embassy in Thailand or consulate in Thailand first.
Get the document issued or witnessed by your embassy translated by an approved Thai Translator. Then legalised at the Thai Ministry of Foreign affairs.
When you find a registry office that will help, get registered at the local registry office if they are willing.
Please note most all registry office around the country will now require you to bring a translator and two Thai witnesses as well. So make before they will allow you to register the marriage with that..
in conclusion, the waiting period is a joke but you better never tell the registry office you know it. As they they will never register your marriage. Most staff in the office are great. But they must report to their bosses and their bosses are there because they know how to keep their bosses happy.