Lining for cat carrier?

I'm going to drive the cats down to Springfield, which is an eight-hour drive not counting breaks. I'm planning to line the cats' carriers with puppy pads in case they have an accident. Do you have any ideas about something that I could put on top of the puppy pads to make the floor soft to lie down on, but still absorbent? I suppose that I could add an extra layer of puppy pads to make it softer....