Vinyl for floor time?

In the past, I've used a shower curtain on the floor during floor time to prevent any accidents. This worked pretty well, until I discovered one of my pigs had eaten a decent-sized chunk out of it one day. It's been a week or so and she seems completely fine, but it got me thinking.

I was hoping to switch from a shower curtain to a thicker cotton-backed vinyl on the floor, just for the sake of ease of setup. I've started covering the thing completely in towels (may change to just a layer of fleece, but fleece is expensive) to prevent any consumption of the shower curtain.

If my pig finds her way under the towels or whatever I decide to put down, will the shower curtain be safer for her should she take a nibble or two, or will the thicker vinyl be alright?

I don't want this to come off the wrong way, I definitely plan to take every effort to deter Ani from eating the vinyl. Problem being, if I just put towels down, there's always a little bit left exposed and if the pigs get bored enough they can burrow underneath the towels. I keep close supervision over the pigs during floor time, but I would like to feel safe leaving the room for five or ten minutes without having to worry about choking or digestive problems or even death from being typical curious pigs.