My concern is her need for absolute quiet and need for me to pop back in. It works well now but I'm going to begin babysitting 2 children soon and I just don't know how the naps will work. I hope she can get used to more noise in the house!
I also put a pretty noisy box fan in her room and it drowns out a lot of the noise outside her room. We have a neighborhood full of kids who are out of school for summer now and make a lot of noise outside our house. This was waking her up until I put the box fan in there. It's an old school metal box fan that makes a lot of noise, but since it's constant noise it doesn't wake her, just drowns out all the other noise in and out of the house.