Doh! I wish I had known about Nancy's.
I *just* bought one similar to the second front pack, but with no window. The one I found did have a removable liner though. (Well, by removable, I mean you can pull it out - like, it's not sewn to the bottom of the bag. It's still sewn in place though at the top.)
I've found that if I put Eva in a tray of yesterday's news for about 5 or so minutes before letting her cuddle, she gets all of her business done ahead of time though.