I would still choose not to practise. Either way, as you said, it is likely to throw him off for a bit, so I would rather keep him as well rested as possible before the trip, and then just go for it when we get there. On trips, Riley is a lot more adaptable than at home, he has an easier time accepting new things away from the house. But that's Riley, I am sure you know what is best for your son. I would be just too afraid of Riley getting overtired before we even went anywhere. On the trip, he will have no choice but to cope, kwim?