YOu don't need a "sleeper vehicle" in my opinion..
Hi Lacey --
If you're traveling a lot of miles, you'll be in the vehicle for a long part of the day. I always like to get out when it's time to stop -- so having a vehicle that is set up to sleep in isn't really required.
My opinion is that having a vehicle that you can sleep in, in a pinch, is reasonable -- but you really don't require one. And I prefer having 2 folks in the car awake, rather than one driving and the other sleeping on long drives. (With 2 people awake you have 2 people with eyes on the road, or one person to grab softdrinks, read the map, and talk to keep the driver's attention on the road or just keep the driver awake.)
For a vehicle? For 2 people a mid-sized car should be all you really need, and you'd probably be able to use a compact car (although you'd be much shorter on volume). If you *Had* to sleep in the car, you could recline the seats and nap out -- but it would not be a good nights sleep, although its doable. A mid sized car is probably big enough for someone to sleep curled up in the back seat, with the other in the reclined passenger seat.
Other options would be a mid sized or small SUV or the like which has more cargo room, plus enough of a flat back area you could sleep in it if you needed to. (I recently met someone who slept in their Honda Element...) Minivans are a good option for some sleep-in-car camping for 2 (although I'd still perfer a tent and a campsite to stretch out). And I've even seen folks who have a mid-sized pickup truck where they sleep in the back of the truck at night (or even pitch their tent in the back). So lots of options, other than a RV.
Camping should be a reasonable option for 2 females around the US, particularly if you are staying in established campground such as national park campgrounds, national forest campgrounds, state park campgrounds, KOAs, etc. Most are pretty well run, and populated largely by families -- so you will have neighbors within earshot.
Safety for solos and women
Lacey, there have been many discussions on the safety issue....especially for women traveling in pairs or solo. You might do a search on the forums and you will find many posts with good advice.
I travel solo and I camp. It's never been a problem. Use good common-sense and, yes, camping near families is a very wise idea. You'll miss out on some solitude but you will feel safer and I believe you will be safer because family-type people tend to take single women a bit under their wing.
My best advice: Don't be paranoid but DO keep your personal safety radar on at all times. If you're uncomfortable going into any situation at all, no matter what or why, remove yourself quickly. And use good common-sense.
With those basic pieces of advice, you should be fine. Of course, life doesn't come with a guarantee, but the odds will be very much in your favor.