It’s more than likely that the covid extension will be extended, obviously this can’t be confirmed until the government announces it, but the situation right now isn’t great so removing it would be a little crazy.
When he leaves, he can use the current visa extension before the end of September which would give him another 60 days 👌🏻
I think there would be an issue with the country that you’re going to, Myanmar for example, would require you to exit their country using the same passport with which you entered. Then the Thai passport control would check your stamps in that passport.
I only have one passport so I don’t know personally but I briefly read a post of a friend of mine who had a similar issue.
Samuel Fila Later is better, 10:30 is the best time to arrive as most of the queue has passed through already so just a few people in front of you = small waiting time.
If you go earlier than this then you'll be stuck in line with the rest of the people that thought it would be a good idea to go early. This, of course, excludes the very first few but who wants to wake up ridiculously early, wait outside and wait inside?