If you are filing soft power I would bet you're chance of getting an interview when you come in is higher with a large amount of visa exempt/ extensions. Just my opinion.
If carrying and declaring more than $10k (and really any large amount) from the US you should have a paper trail in your possession. There are a few reports of DHS doing seizures until you can prove where the funds came from. I would SWIFT the 800k.
Yours says "Remote Worker" in the comment field no? His doesn't. It is blank. He has a Workation DTV but there is no mention of the type of DTV he has on his VISA.
That's not true. I have a friend who got his through the Washington DC embassy/consulate and his "Remarks" field is empty. He has a Remote Worker DTV like myself. Mine says remote worker.
Considering you are telling the Thai govt that you need the visa so you can participate in the soft power, they could say you are in violation of the terms of your visa if you no longer are in the course or going for care. When the IO asks, what do you do? Lie to them and hope nothing happens?