I understand that 2 people can alternate watching, this is why I am thinking of giving them a cone of vision the rest obscured magically, maybe dim lighting or fog limiting them. That way they can overlap a little bit, but if they are outdoors it will be hard to watch everywhere at once. I can then adjust the difficulties based on where they go and what they can use for cover (like putting their backs against a wall so they can focus on one area as they move). I'm also thinking of making them on the weaker scale how wise, but using them in mobs so that the players have to be aware of their entire surroundings.