Whole Foods Market and Wild Oats Marketplace have stores countrywide in most major cities. They have delicious prepared foods that you could eat there or pack into a cooler to take along.

http://www.wholefoodsmarket.com/

After you have firmed up your route you can post again with specific cities that might have restaurants that you'd enjoy.

Also Trader Joe's Grocery stores are found in many states as well. I have found that more and more large grocery stores are carrying organic products.

Give us your route and we can help a bit more.

If you are going through New Mexico, Santa Fe has Whole Foods, Wild Oats, Trader Joe's and a few smaller healthfood markets. Also a great Farmer's Market on weekends and Tuesday mornings. You could also find restaurants that would have items you could eat.

As stated when you have your route, post in the specific forums where you'll be visiting. Here's a recent thread to illustrate that there are gluten free restaurants around, even TexMex tripadvisor.com/ShowTopic-g60956-i76-k202348…

Many towns have farmer's markets on weekends, especially in August. Depending upon where you are, you will probably find roadside vegetable stands.

Also, don't totally despair at "fast-food" places -- many of them serve salads and grilled chicken sandwiches now. (Just toss the bun). Buy a bottle of organic/suitable dressing in a store and keep it with you, you should have no problem bringing it with you into a restaurant.

Another thought might be a buffet that is heavy on salads. Souplantation / Sweet Tomatoes is wonderful:

http://www.souplantation.com/locations/fm/

Another place may be Golden Corral, they are in many states. Great salad bar. Check the menu items:

http://www.goldencorral.com/menu/hot.asp

Definitely check the above grocery stores. You may also find many large stores have an organic or natural foods section.

Stop by a Walmart, sporting goods store or larger drug store (Walgreens, Rite Aid, Longs) and buy a small ice chest / cooler, re-freezable "ice" packets and zip lock bags. You can fill up the bags with ice at motels, or refreeze the "ice" bags daily.

Subway will make any sub into a salad, and there seem to be almost as many Subways as McDonald's many places.

As to your gut problems, are you sensitive to MSG? You may want to go online and check out the MSG contents of salads at different places. I'm pretty sure Wendy's salads are heavy on MSG. (I don't usually worry about it but I've learned Wendy's salads and KFC mashed potatoes can give me grief).

If passing through Northern Arizona, stock your cooler at New Frontiers Natural Market in Flagstaff. It's right on the "main drag" (Milton Road). North of Flagstaff the pickings get slimmer for healthier fare. The Super-Walmart in Page (Lake Powell) has a fairly decent produce section, and there is a good sushi bar there too (don't recall if you said the fish had to be cooked...).

I would visit the websites for Whole Foods and Wild Oats. As mentioned, those two companies have stores nationwide and you should be able to identify the locations along your planned route. In addition, as Dragonflylady said, in Flagstaff and in Sedona you can find a comparable store known as New Frontiers.