"I am not sure, though, about something that only sits on front teeth, I would think that would put all the pressure on one small area and cause it's own set of problems. "
You would be right. A nightguard needs to cover all of the teeth. If you don't cover a tooth, it will move outwards away from the jaw. With your history of unstable teeth, that would be a nightmare waiting to happen. You are skeptical about what you see on tv or read online, keep that trait!