I don't know, that might sound just obnoxious to you, but on travel days I make sure to already drink at least a liter of water before I leave the house, even if that means chugging three glasses in a row at 4.30am... from there, Hydration almost works automatically as you are reminded of drinking once you hit the restrooms and also just follow your thirst and will end up hydrated due to the head start you had.

Do you like tea? Sometimes having a teabag in the bag, and getting some hot water can be a nice alternative to just drinking water. It can also be a wonderful morning or bedtime ritual, even when traveling.