I'd suggest to sent your luggage home by courier (maybe to your neighbours, just in case you do arrive home later then your luggage) and do only OLCI for the leg JFK-HKG. That way, you don't have to face the check-in desk handler with maybe nasty questions. Why do you, etc.
You still have a chance for the red beep at boarding though and CX insisting to check your passport for a proper VN visa at that moment.
Expect CX to be aware many of these lucky F/J passengers are trying to skip the last segment and CX may have a temporary enforcement on the VN visa check at the US departure, being checked in for the final leg or not.
There is no such thing like a free lunch, so to say.