Older Dog behavior

We have an older female dog (cockapoo) that just turned 17. She doesn't see or hear to well and she is starting to show the affects of being senile. She still eats well and she is pretty healthy. A year ago she started to have accidents in the house. She does not have a problem urinating or moving her bowels other than she is now doing it in the house. We let her outside several times in the morning and night and twice during the day. My wife and I both work so we keep her fenced in, in our kitchen. It's much easier cleaning up the mess on the tiled floor than on the carpet. However, she often messes than walks through it and tracks it all over the floor and all over her paws. Her and our floor get a bath several times per week. We started covering the entire floor with brown paper. This makes it a bit easier to control and to clean when she messes. We tried a doggy diaper, but feces were still able to slip out through the whole near the tail. Do you have any suggestions?

Is her quality of life good for her?