Hello, I'm not familair with a tray that goes in the bottom of a playpen... the breeder I got our girls from gave me a 42×28 wire crate with pull out tray under the 'wire' floor... I've seen similar crates in stores and these playpens look nice for during the day...
Amazon.com: Blue 45" Pet Puppy Dog Playpen Exercise Pen Kennel 600d Oxford Cloth: Pet Supplies