I just left the local immigration office somewhere in Northern Thailand. I already have non-immigrant O visa. I have proof of 65k in deposits for the past year. Still not good enough. They would only accept an embassy letter or salted 800k.
The exchange rate is about the same and if using Wise to transfer under 50k the funds usually arrive in seconds on weekdays but can be delayed on weekends due to banking hours, I guess. Also, for purposes of verifying monthly transfers for retirement extension Immigration only accepts bank statement. Wise transfers directly to Kasikorn Bank so bank statement of Wise transfers are available. ATM withdrawls are not accepted by Immigration. At least, that's been my experience.