I wrote some time ago that I believe JLM learned from the discovery of Morgan's body, and if found on a property it would be one where no one lived or worked. I can't say from what Longo described if he meant out in the open or within a structure, but I'd be willing to bet there are structures on the property that haven't been occupied for some time. Because I think JLM learned not to dump his victims in areas where they are likely to be located, to me that would include out in the open. So IMO she was found in an abandoned structure of some type and (again JMO) somehow hidden within that structure.