The important things! Clothes so you don't get arrested, and your all important pet.
I would make sure he doesn't fill the container. And that is correct on the just put the water in the ttravel container, but I know most people want to totally pamper their guys. I would just bag mine and take them otu for exercise and water at the motel. Give them a rubbermaid for overnight. But then my guys are so mellow that I hang them on me 75% of the time anyway.