hmm...it seems that it didn't go as smooth as anticipated with a delay of the USM-BKK flight. The OP made it but most likely wasn't comfortable with the initial delay (I wouldn't have been). Thanks for reporting back/indeed, very useful.

Did you try to request the bags to be checked through to final destination at USM? (I know def. not given when on separate tickets and different airlines). It may also be that PG is not able to offer C.I.Q. transfer from USM.