What are the re-entry requirements for a US passport holder on a 6 METV when traveling from Thailand to HK?

From my experience with Jomtien they are a little lenient on the 24 hrs

You are highly unlikely to be asked for ANY of the 3-proof-ofz when flying into the country on a 6 month METV (however you certainly could be asked). I would say have proof of funds just in case (as that's the main one they ask for IF they're gonna ask for anything).

You have 24 hours from when you arrive at where ever it is you call home to go file your TM.30 (if that immigration office requires it AND jomtien does). So you have until the next day after you arrive in Jomtien to file it