I feel that asking to overnight at a church is putting a lot of undo pressure on that minister. Of course he wants to be the nice guy and say "Yes". But it is an imposition on both the church and the neighborhood. And what would your opinion of the church and the minister be if they say "Sorry"? Churches are welcome in neighborhoods precisely because they do not have much traffic or activity except on days of worship. The neighbors are likely going to have a much different opinion of the church as a neighbor should the church start having strangers camping in their parking lot. I know there would be hell to pay (pun intended) if the churches in neighborhoods near my home started allowing overnight camping in their parking lots.