Hello Andrew It's a long time since I had my last Commer but you are right, the gas cylinder must be turned off when travelling,can you imagine what would happen if someone ran into the back of you, you or your passengers were trapped and a fire started. These cylinders are like a bomb when they go off. You will find that your fridge, if you have one will actually run on either gas or electricity,so you can switch it over.
If my memory is playing tricks then I am certain one of the other members will correct me. Not about turning the gas off because anyone who doesn't turn it off at the bottle is worse than a nutter and that is a retired fireman talking.Enjoy your trip away and be safe.