This is a beautiful idea, now that we know how it works, we can help each other. Unfortunately I'm past the ancient skeletons and don't see them in my manor anymore. If I can manage to get past the next one, the vampires, I'll try my best to leave my vamp at as low of a level as I can for peeps to use when they get to him.
I think the game resets them, though. I had a friend earlier today have one at 1/10, so I asked her not to banish him so I could use him, too. She agreed, but by then he had disappeard from her manor (from her view), but he was still there at 10/10 when I visited her. We can't ask people to not completely banish them though because they'd not get to do the next monster quest, and we only have three more days, right?