You would have to book a separate BOS/LAX flight and take the redeye back to BOS to start your BOS/ORD/PEK flight. Does the flight back to BOS get you in time for the BOS/ORD leg. Since you are PLT you would get use of the AC and BOS luckily has showers (as does ORD and LAX.)

Otherwise, come up with some bs reason to postpone your meeting.