Never had a problem in a truck stop from a security point of view. Some of them can be noisy with refers running, sometimes trailers being exchanged, sometimes flats being fixed, etc. In the middle of the night they're a hand place to catch some sleep and you need fuel anyways.
Just don't hang a slide out all night, one of the trucks backing into the slot next to you might not see it and hit it. Some truck stops can be almost empty when you pull in and then fill up during the night. If you need to put a slide out, park on the edge of the lot so the slide is hanging out over an area where a truck won't park.
Bill