Odie, I am sorry to hear about your experience. I don't blame you for your response. I do hope that yours is a rare exception.
Over the years we have found that most of time when we are ready to park for the night, when we are near a comercial or manufacturing company parking lot, when we ask, we get permission to park over night. Since it is always evening, and often the lot has a security person, we are welcome with the instruction where to park and what time most employees arrive for work the next morning so that we can be out of the way.
If I may give an example, about two months ago, near Springfield, MO, we stayed overnight in a company parking lot. The Security agent, in his pickup truck guided us to the back area along a small stream, where there was a shade tree and a couple of picknik tables. We assured him that we would leave by 7 AM when employes would be starting to arrive. A few days later, on our way back home, we stopped at ElDorado, Kansas where the Ford Dealer gave us permission stay overnight in the rear area of the the Ford Dealership. We had the large area all to ouselves. Just before dark a local policeman stopped by and told us that he would be by through the night and keep watch for us. He had a cup of coffee and a sweet roll with us as we visited a few minutes. We invided the policman to visit us in Colorado if he and is wife ever gets out our way.
There have been a few times when the business declined to give us permission to park over night in their parking lot. We have always been polite when declined since I understand that it their property and, as with my own, everyone has the right to control their property. I would estimate, over the years, at least 80 percent or more of those businesses who are asked do give us permission to stay overnight on their parking areas. When we arrive after business hours, after employees are mostly gone home, and meet a Security person, we almost always get permission.
I look at the parking situation about the same as I do on our ranches when strangers come and ask for permission to fish or hunt. I have instructed my ranch foremen to give permission provided the hunter or fisherman shows an NRA membership card and understands the rules we need to protect fences, livestock, etc.
It is not hard to determine if the person(s) seem to be respectable and we have had no problems with our own system.