After a lengthy meeting with senior Immigration officials from Regional 4 district, regarding clarifications of the amendments to Order 138/2557 and the new Order 35/2562, I can confirm the following;
2.18 Marriage extensions.
Funds deposited in a Thai bank.
400K deposited in a Thai bank for 2 months prior to the date of application.
Passbook or bank statement + bank letter as proof.
After the extension is granted you can withdraw part or all funds.