Shampoo Bars are very handy for travel as they can be used as both shampoo and body soap.
I recommend rinsing your hair with Apple Cider Vinegar after washing your hair with a shampoo bar. It will close the cuticle, restore your hair's pH and add shine. You can add lavender or rose petals or any herb or flower you choose to the vinegar and let it sit for a week or so and then strain before using. While Apple Cider Vinegar is less processed and contains trace nutrients, white vinegar will do if you don't have ACV. 1 part vinegar to 3 parts water and you either pour over your hair or put in a spritzer bottle and spray it. Rinse well with warm water. I prefer to spritz it myself.