I have been with a problem. My little man seems to not have the best aim for the system. So I have been having messes to clean. My solution? Plastic.
I wrapped the inside front wall and the bottom edge of the front and left side with plastic.
And then wrapped the plastic thru the hole.
I left a flap of plastic to hang down.
Now when my son's aim is off, sometimes horribly, it will be much easier to clean.