Parking, yes. But officially you can't stay the night in the parking lot in your RV. Walmart used to allow it, but they've been cutting back at certain locations because of municipal regulations. There are signs that say no overnight RV parking. I have heard anecdotally that you can talk to a manager and get permission, but it may depend on the mood of who you talk to. So you can ask, but have plan B if they say no. As far as safety, it is a very safe area.
It is a pretty busy parking lot so finding spaces may be difficult unless early morning. Might be easier if you go around to the back to park. Most people don't know there is space back there
It seemed to me that it is ok to park an RV there. I saw a couple parked there when I went shopping.
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