I met one of the editors of Adventuress Travel Magazine last night.
From the site:
We are women over 50 doing fun things….
Here you’ll find essays of true experiences to stimulate the adventuress in you—I know there is one!
Plus, here we talk about food and books and films by and for women who love to travel and have had adventures in their lives that will thrill and entertain and inspire you.
Interesting section on travel books and lots and lots of adventures by intrepid women.
I recommend you take a look -- the vast majority of solo roadtrippers on this site are women.