CW accept accounts that do not have a bank book.
If you plan to obtain a non O based on marriage from a visa exempt and subsequent extensions you are making simple difficult by using SCB.
You do not need to show funds came from abroad for marriage.
When are you planning to do this?
For extensions marriage the funds only need to be in bank for 2 months plus under consideration period. After that they can be used.
Surely the interest earned cannot be reason for SCB account over convenience
I use Kasikorn at CW (retirement) and do the bank letter, small deposit on day of application and 12 month bank statement day prior (can be up to 7 days prior)
Banks at CW open at 8.30am