My only concern was I've never pulled the covers up to my chin in a public parking lot before. Just wanted to know if it was safe.
I've done it a grand total of twice now, so speaking from "experience," I felt safe because there were a few other people parked in trailers/RVs near me and because people came and went from the Wal-Mart all night long (including, in both instances, zamboni-like parking lot cleaners). Of course, that's the down side to it - I felt perfectly safe but got almost no sleep the first night because it was pretty noisy. The second night I was so exhausted I slept through the traffic, the zamboni and the 24 hour security driving around the parking lot. It was OK to do in a pinch during a cross-country drive, but I don't recommend it unless there are no other options available.