I travel across the country on my own several times a year, and have been doing this since I was in my 20s. (I am now in my mid-60s).
A few rules I follow are:
ONLY GET OUT WHEN THERE ARE AT LEAST A FEW OTHER CARS AND OTHER PEOPLE RIGHT IN THE VICINITY
This includes rest stops. There are cool, disposable, biodegradable devices now for women to relieve themselves that are sanitary and turn liquids into gels. I carry these and use them overnight and at other times if necessary.
BAG LADY IN PINK
I don't wear makeup or do my hair, and I wear really baggy old clothing that is not flattering in the least. So I look very unattractive.
But...I ALWAYS wear pink. I have done this for years. Research shows that when you are wearing pink, people think you are a sweet person (if not too bright) and are kinder to you. I learned this through much experimentation over decades. So if I have to ask for directions or help, people are inevitably nice.
When I was younger and traveling at night, I would tuck my hair up under a baseball cap so my silhouette looked more like a guy. I don't do that so much now that I am older.
WHOSE CAR IS THAT?
I strew things around my car, including several big plastic bags holding stuff. One says GOODWILL on it. I make sure the car looks really messy. While my car is always a little like that, on long trips, it is purposefully messy, like leaving a travel bag half open with clothes hanging out of it, although in truth everything is highly organized and I know where everything is. A perfect car with perfect luggage is a lure for thieves. My car is not a lure. Potential thieves don't know that I am often carrying not only thousands of dollars of equipment in computers, recorders, cameras, etc., but sometimes literally thousands of dollars in cash (when I have been paid in cash).
CAMPING
I do like to sleep on my futon in the back of my car, which is a station wagon. It is more comfortable than a motel bed! I just bought an exquisite memory foam topper to make it even more comfy, and can't wait! I have rules, however, that I got from a female truck driver.
First, never overnight at a rest stop (except in Nebraska, where it is customary for a number of people & the rest stops are right off the highway). Go to a big truck stop where there is always 24/7 foot traffic. I always check to make sure it doesn't look like drug dealers are around; having traveled the same routes for years, I pretty much know which truck stops to avoid and which are brighter & better.
Park near the big rigs; more foot traffic, and the truckers make me feel safer. I never get out of the car at night in a place where I intend to overnight, as I don't want people to see a woman alone is in that car. I cover all the windows with black plastic garbage bags (for the rear window, I have to pin them up and use big pins, like the kind you used to get for corsages). When I sleep, I keep the key in the ignition, and a knife, flashlight and cell phone within reach. Just before turning in, I always call my son to let him know where I am.
I actually feel safer in my locked car in a trafficked & well-lit truck stop than I do hauling suitcases out of the car in a dark motel parking lot. Also, for daytime, truck stops have clean showers.
I keep lots of disinfectant wipes and hand sanitizer, etc., in my car on these long trips, too, as I am a borderline germ phobic.
FOOD
I bring my own food, just got a cooler that keeps ice frozen for five days in summer heat(!), and have a wonderful organized system for my meals. You & Lynn probably have your little systems for travel down-pat, too. I do love my own organic, free-trade, shade-grown gourmet coffee! Turns out in truck stops that boiling water is free. Out of courtesy, I always ask, though: "Do you charge for hot water?" They always say no. So in the morning, I fill my insulated mug with super-hot water, come back to my car and use my own little one-cup Melita filter system to make fresh coffee that tastes wonderful. Yum!
DIRECTIONS
I rely completely on the little man in my Garmin GPS! Wow, has he saved me! I also have an up-to-date road atlas and lots of maps for backup, and Triple A with 100-mile towing. My cell phone is a very old, very inexpensive Tracfone where I prepay. The calls themselves are expensive, but this phone is only for emergencies and to check on messages from home. Don't you also have Tracfones? I have been all over the USA, often in the boonies, and with one exception in ten years, have NEVER failed to get a signal, since Tracfone pays other companies for their signals!
I should write a book for older women traveling alone! The wonderful thing about these trips is that everybody always agrees on whether or not we want to listen to the radio & what we want to hear, and everyone in the car is always in a good mood!