As a child care provider who is currently working towards a Quality Rating System goal, I can share that when the consultants came in to check my equipment, they requested that no pack and plays be used in child care - - because there is no safe way to clean and SANITIZE them. In a case like this, with fecal matter smeared everywhere, I'm thinking that your best bet would be to get rid of it. They now make portable cribs that fold up and store out of the way when not in use. They are completely wipeable - metal bars and a waterproof mattress. They can be spendy, but in my case there were grants that the consultant used to replace my pack and plays free of charge. Your provider may want to check into resources available to her.
The other option, since she is two, is to move her out of a pack and play and onto a nap mat or cot (in a supervised area - to keep the poop play in check :o) )
Also, don't feel terrible about it :o) Toddlers tend to engage in this type of behavior, and I'm sure your child care provider is not much surprised by it. Also, without trying to sound too harsh, she's the one who left your daughter awake and unsupervised long enough to create the mess with her soiled diaper. I think it's great that you feel moved to help her with the problem though :o)