The overnight spots such as Walmarts, etc. are best used with a self-contained RV like a class A, B, or C. If it doesn't feel right, you can just drive away without having to exit your RV to get into the tow vehicle. This has happened to us on several occasions where some unsavory characters were hanging around too close for comfort. Just drove away and found a better spot.
We've also used Lowes with success. Flying J's are among the best even though they can be a bit noisy (Shower #19 now available!). But they are safe, IMHO.
