if you use Wise to transfer the funds it asks you how many baht you want deposited, not how many dollars or other foreign currency you want to send. So there's no risk that the exchange rate will cause you to have a subpar deposit.
like I said, it worked for me in Krabi to show 2 months. They preferred 3, but they gave me a break, sort of. The OP should check with his immigration office about what's required at that particular location.
Immigration doesn't want proof of your income. They only want to see the deposits have been made into a Thai bank account. Most immigration offices want to see 12 months of deposits prior to the extension. Some may let you get away with just two or three months for the first extension. You would need to get a letter from the Thai bank certifying bank statements showing the deposits. If you don't have a few months of deposits at the time you need to get your extension it's not even worth trying.