I just did the southern part of my State (CA) in order to bring my daughter to Legoland and the San Diego Wild Animal Park.
I was terrified of finding no food. I had my boyfriend with me along with the kid and a cooler in the car full of bread and soy yogurt and fruit, just in case.
Imagine my surprise that the Legoland Park had an entire Veg restaurant and veg options at all their eateries. The outlying town of Carlsbad had many eating options including woodfired pizza made without cheese in you wanted that way or smothered in roasted veggies,
We made it down there by stopping only at Subway stores and eating Veggie Delights. The Wild Animal park was as depressing as predicted and we did not hang around long enough to eat anything.
The availability of good food in general was heartening to me.
The only real wasteland was the I-5 late at night. Your choices are very limited. We used the bread and the avocados in the car cooler and drove on through.
It's not gonna be a safe world until I can eat as nicely as I did at Legoland EVERYWHERE.