I'd play standing in the aisle facing the passengers... Elbows against seats can steady you in the corners
If you sit down you will face away from your audience, which worked for Miles Davis, but in that coach, with nothing to see, the passengers will not join in with any more gusto than they would to piped music
The health and safety advice that predicts you'll lose teeth, fly out of a window, or be the first to shatter the windscreen in an emergency stop is all very well... but either you are willing to risk the 0.0007% chance of your death by misadventure, or you entertain, stand up, face the party and enjoy their enjoyment