Satun - Thale Ban National Park (Wang Prachan) is the closest land border... Easy to find Google Maps

You can find their FB Page with a simple search. Thai Consulate Kota Bahru

Note their schedule: Open on Sundays - Closed on Fridays

No appointment necessary. Apply in the morning - get the passport back the next day - afternoon.

A good friend of mine - back in early November 2019 went to the LA Thai Consulate. He presented his application for an O-A Visa, paid the fee and presented his proof of health insurance. He gave the Consulate officer a copy of his Insurance Policy which was a year long Travel Insurance policy purchased on the Internet for $110. The Officer looked at it and said he would have to have the Big Boss upstairs take a look. The Big Boss did review it by Internet search. Checked out the company - policy wording and coverage. Being satisfied the Big Boss approved it. My friend got the big O-A sticker in his passport. He entered Thailand in late November - stamped in for one year.

Yes - clarify with your Imm office beforehand. Also be sure each monthly transfer deposit in your account is labeled "International Transfer Deposit" and encoded as FTT in the Bankbook (Foreign Telegraphic Transfer)

Last year the local Imm. Office told my fellow American friend his only option was 800K in the bank since the American Embassy Bkk no longer issued the Income Affidavit. Immigration was dead wrong but nothing could be done about it.

One critical question: is there proof of 12 previous months of receiving 65K Baht tagged as "International Transfer" into a Thai Bank account for the primary person. Get that done then apply for the "follow on"

For the nearby Thailand neighbor country to get another Tourist Visa I recommend Penang / Georgetown, Malaysia. This old British influenced area is an interesting place. It will add nicely to your South East Asian visit

My advice - forget the road blocking Thai Bureaucracy - go to the Thai Consulate in Savannakhet and get married there - then get a One Year Multi-Entry O Visa for Marriage. Or just go to some other location in Thailand where they don't have this idiotic rule and get married