You would have to do two “border runs” out of Thailand, but a 6-month, multiple-entry visa could give you up to 9 months in Thailand with a LOT less paperwork.
Does the money in your Thai account for a long period include the 800K or 1.6M needed for the visa? Do you still have proof it came from an international transfer?
If you go to the information window at CM IO they will give you the instruction sheet and the necessary forms. The instructions don’t say it but you must have TWO SETS of all documents. And it’s AT LEAST 21 days remaining. It was 23 for me because of 2 holidays.
He is arriving on a tourist visa which should be for 60 days and didn't state what immigration office he will be using. Isn't the first 30 days too early for the many offices which require 30 days or fewer left?