Ok. You can be on a tourist visa for up to 90 days. Then visit a Thai immigration office to ask for your mariage Visa. You will then be granted a 90 day « temp » mariage visa before you get your 12 months. This 3
Months granted « temp » will give you the right to open a bank account. Also, some agents are helping out for your bank account 😉
If you don’t have multiple entry and you go to Cambodia without advising immigration first, will they cancel your 12 months visa upon your return in Thailand? Then you will have to go through the process of getting a new visa? How about visa extension?