Thinking bit more than 4k currently in Bangkok for agent to open bank account.
CW is unique in that to obtain certificate of residence they require a TM47.
The OP has tourist visa so that is not possible.
An agent is the solution.
Bit unrelated but even more difficult is TDL as in Bangkok that also requires a COR.
Agents such as Fatboys, BSR, etc cannot obtain a COR.