@scoop I sure do relate with your impossible dream to make this process quieter! I don't see anyone with responses to this quest, but just know that you are not alone. Traveling presents issues with finding a private place (sometimes in someone else's home, sometimes when sharing a room, sometimes in close quarters) to do the requirements of airway clearance WITHOUT exposing others to the sounds or other details! The only tip I can share is that sometimes a car parked outside has been my privacy refuge. And then I worry about what passers-by think I'm up to...
Hang in there!