No Need to be Rude.
I have worked in customer service for nearly 2 decades. I know customer service and sometimes you do have to tell the customer no but there is no reason be be rude about it.
I am an RVer and Walmart is a place that generally is a great stop for a night when traveling and you don't want to stay for long. We pull in at night and usually only spend long enough to sleep and eat and then we are back on the road. We pulled into this Walmart. There were no signs saying we could not park there so we pulled in. We walked in and did some shopping as we do when we stay somewhere like this. We went to the manager to ask about staying for the night and the manager was just rude. There is no overnight parking in their lot. It's all fine and good that they do not allow parking but the manager did not have to treat us like scalawags. We will not be shopping here again. We will make sure all of our RV friends know this is an unwelcome place.