We have the Potty Training Puppy Apartment and coordinating x pen. It is really tall and so far, Katie Scarlett hasn't even tried to get out. She rarely even gets up on her back 2 feet when I put her in. This has worked great for us, but it did cost a pretty penny as we say in the south. LOL. But it has been worth every penny for us. Katie Scarlett has done fabulous on her potty training. We got her at 12 weeks. She is almost 5 months and is fully potty trained we think. She hasn't had an accident in weeks. I've started letting her have free range of the house for small periods at a time and so far she has gone to her pad every time she needed to go. But the coordinating x pen is great. It's taller than the crate and I don't see how she could get out. But I know these little cuties can be little Houdini's. I just hope KS won't figure it out. But also, we really do not put her in there very much. She mostly stays around the house with me since I am a stay at home wife.
www.modernpuppies.com
Sorry I couldn't be of more help. I hope you can find a good solution for you and your Yorkie!