I hear this loud and clear. I too, cannot drive on any major highway and always need back roads to get to any location, or I go out at the crack of dawn. I'm lucky I live in a small town out in almost the country.
However, some days, it doesn't matter. I found that having something personal- a photo of something I love helped. Also, I have stuffed animals from friends/family collected over the year. I will take one from someone I know did something SO difficult and use that to help give me strength.
But those are good for short trips. Long trips - definetly a cell phone. When I started driving more, this helped me WONDERFULLY! Secondly, can anyone go with you? are you nervous being in a car with someone? Perhaps a family member could come your way and help you get to visit family?
Good luck and don't lose faith in yourself!!! I think all of us with PD get that way- we are farrr too hard on ourselves!