First thing comes to my mind is insurance. I don't want a stranger spending time on or in my property overnight. If they get hurt, guess who's paying for it. It all sounds strange it me. If you want to see it during daylight your welcome to take a couple of hours looking at it, with my attendance answering questions and a drive if you wish. But going over manuals and all the other stuff. When you write the check you can read and tear it apart all you want.
It'll be setup to show everything works. That's the way it happened when we purchased our new MH. I couldn't sleep it that either. The warranty covers any future issues on a new unit. Your pocket book would in this case. It's a chance you take.
Buy the way, just a observation for what it's worth. You aren't going out of your way to make friends either ;)