[alaskayorkie]

I don't think you have to have a crate if you've got a good sized pen. You just want a comfortable amount of space between the area where they sleep and the area where they poop.

People recommend small crates within the pen to reinforce the idea that that's where they sleep, and the other side is where they poop. However, if you set up a few blankets instead of a crate, I don't see why that wouldn't work. Another benefit of a small crate is it's nice to get them used to it and comfortable in a crate. You never know when you'll have to transport them in a crate in the future.