I carry these gf cards with me all the time. They are extremely useful in explaining that this isn't just a whim of mine but something with serious health consequences. I have them in several languages, which is a huge help when I'm traveling overseas and don't understand the local language.
I tend to pick up salads and such at the local deli counter and avoid freeze dried meals because so few are gf and they all have too much salt. Besides, I love cheese which ups the salt content quite a bit. Small cans of salmon or tuna can compliment a plain salad beautifully and there is no need for cooking.
I always have lots of gf bars in the tank bag for snacking. My latest fave is the KIND fruit and nut bar.