Spending a night (or two) in a motel parking lot?

We have stayed in motel parking lots in our Class C. Most business owners welcome someone spending the night in their parking lot as an extra set of eyes for security.

We even asked one motel if we could plug in, they answered that a plug was available at the base of their sign for just that purpose for a $5/night fee. Apparently the plug was installed for use by a refrigerated ice cream truck.