Can I get a 45-day visa stamp at the Ranong border currently?

Correct, although only the airports open . Strangely, not a single land border Thailand shares with its neighbors is open , which in my opinion is just stupid. Malaysia and Singapore share 2 border crossings and they're open .

I think keeping the main land borders open would be more important than the airports being open late at night, as local people crossing for medical reasons or other urgent matters could cross at night. Also, if you arrive on a flight at 3am, the airport rail link isn't running, you're forced to catch a taxi because no one wants to pick you up, hotel clerks are asleep and some hotels don't let you check-in until 2pm anyway, so it's not great to arrive in town after 11pm.

Been a couple of reports from people that have done the bounce there. You need to show covid vaccination or do a test there.

45 days until midnight tonight after that set to revert to 30 days for exempt entry.

Got till midnight.