If you are Thai (Thai passport), you need a Schengen tourist visa. Then you can stay 90 days (per 180 days) and travel free to other Schengen countries.
Know nothing about the sport itself, but to be sure I would email (so you have some answer on paper) the USA- and Thai customs about this. Also possible to order them with e.g. Lazada. There I see that a lot of them are sent from Bangkok, so these ones are already in Thailand. Good luck !
And maybe a little bit more expensive, but you can transfer it in a couple of parts as international transfer. Only thing is that you reach the 800k฿ 2 months before you ask the extension (not end date of visa)
Maybe a tip, despite living close to the imm. office, to register online for the TM30. In future, you can do it yourself and not have to go to imm. 🤷♂️
Okay, but he asks for a multi entry tourist visa. So I think original plan is 3x 60 days with border hops/bounces. When he does that right before the visa is void, he gets another 60 days. So you can get almost 9 months of stay with this visa. Most of the times without much problems at the border.
Pfff anoying indeed. Just to know, should you enter on 30d visa exempt and y'r visa comes in when you are already here, it's possible to do a borderhop en return with the visa.
One time a problem that my money not came in as usual. Sent mail and they said that the "deemoney interface" was added and that they are more strict in the correct name of the account. 2 times they send my money back. After I changed the name of my bank account exactly as on my bank book, everything went fine again. Really do not understand problems. They also have a phone number. Always correct.