Need a cleanable poo mat to put under xxxlarge dog crate?

Hi there, my great dane has a sensitive stomach and will get bad diarreah. It will last three nights and go away and will be back again. Im sick of getting up at 3am cleaning diarreah from my carpet because it splatters out of his crate. I was thinking I need some sort of wipeable flat mat to put under the crate and half up the walls for protection for when this happens again. I thought of a computer chair mat but its not bendable to put up the wall. I dont know please help me!