I guess it depends on where you are at. A couple of weeks ago during a 1 week trip we Wally Docked every night (in fact two nights at one of them because of rain) we parked very close to signs of this type. Most Wal*Marts in this Province have them. Actually I just wanted to prove a point.
Click--> The last night on the road we stayed in a small shopping center lot. In the wee hours, my wife being a light sleeper heard a discussion outside the van, between someone who wanted us out of there and security who said we were only stopped for the night and they would see that we were gone before the stores opened. Now bear in mind this happened in a Province that has a law that is stated on the Wal Mart signs. The thing about this is if you ask, then the answer will be no, if you don't ask then it may be OK, but in any case be prepared to move if asked.
Just a thought from our experience.
Cheers Willis