Are you taking an ice chest? Or even a little 6-pack cooler? You can put a cup of ice in a zip lock bag to keep a small cooler cold. If it's a road trip, there shouldn't be a problem with stopping at a grocery store and hitting a deli counter for some Boars Head Meat. The Honey Roasted turkey is good. I frequently take lunchmeat and crackers (Nut Thins) for lunch at work. And you can pick up fresh fruit or fruit cups while you're there. Make sure to ask the deli person to clean the blade before slicing your meat. All Boars Head Meat is gluten-free but they usually sell cheaper stuff that may not be.
http://www.boarshead.com/faq.htmlIf you hit McDonalds, they have a gluten free grilled chicken breast that is very good and you can have their salad. Just make sure you talk to a manager and emphasize that your food can't touch bread and how sick you get from gluten. In my experience, the managers get it, the person behind the register may not.
http://www.mcdonalds.com/mcd_apps/nutritio.../glutenfree.pdfTaco Bell seems to flunk gluten-free but other fast food places have gluten-free menus. I don't know what's in your area of the country but spend some time checking it out before you leave and take printed gluten-free menus with you so you won't get somewhere and be tempted. Most places, the manager will know what you're talking about. When you get back, dropping an email to the corporate website praising or lamenting your experience can go a long way on PR.
If you want to only eat food you bring, Jif peanut butter to go cups would be ideal for travel. That way, you also limit the chance of cross contamination to your supply. I've had to write off big jars of peanut butter at work because someone didn't understand that dipping their gluten contaminated knife in my jar would be a problem.
http://www.jif.com/products/details.asp?prodID=572Dinty Moore is gluten-free and can be heated up in a convenience store using their microwave.
Also, when I had to sit with family members in the hospital, I took Turkey Spam singles, crackers and apples. It's not as good as Boars Head, but it requires no refrigeration.
Having said that, I agree you should pack along the gluten-free bars as insurance and the standard Celiac travel equipment -- immodium (just in case).