Yes, with the delay the connection was tighter than we were comfortable with (especially given the luggage delay). However, I had stuck with our flight (which was a daily-scheduled A319) instead of the next-earlier flight (which was a periodic ATR-72), which to me was a good call - our flight was indeed full and was clearly a priority. If our BKK-HND flight had not been a little delayed, at normal walking pace we would have ended up at our departure gate after the boarding process had started. So the original three-hour scheduled layover, with long delays in both the flight and the luggage, ended up being just enough.

I asked twice about checking through from USM but was told that would not be possible due to the domestic-international-international itinerary - we would need to clear luggage domestically before checking the luggage internationally.

FWIW, we were told that the Thai cutoff for international luggage was 40 minutes before departure time, though based on our interactions with the staff at BKK, my guess is that they would even push that cutoff some more for a business or first ticket.