Fleece Piggy won't stop burrowing!

I am currently using carefresh, but i really want to switch back over to fleece because it will be cheaper (although a little more work). I once used it, for only a few days. My piggy, Aela, did not handle it well. I came back from the store and i couldn't find her. Come to find out, she was under the layers of fleece and towel. She could suffocate!
Can somebody give me some suggestions on how to stop her from burrowing in the fleece? I really want to go back to it, but it worries me that she'll get stuck or can't get out.
Thank you!