I dont have any solution, but I had these when my oldest was a baby cause we only had hardwood, after trying to constantly clean spit up and avoiding walking on them, and my son always ripping them apart, I got rid of them and got a big area rug with a spill proof thick underpad for floor play for the little ones.
Cleaning them was the worst, I would just spray and wipe them down with an anti-bacterial all-purpose cleaner.
Pain in the ass those things are. I'd be curious to hear other's solutions