I think you need to specify what low ratio is in your ads. A LOT of home daycares use this as a selling feature...but they mean the full 5 kids. So in your advertising title put 1:2 or 1:3 as your ratio so you only find the families that want this.
It may or may not be a selling feature for families. Some love it...most want closer to 5 kids so they are in a more social setting. It will likely take more time to fill the spots but save yourself the time of having them arrive for an interview thinking you'll have 5 kids.