I'm installing Lifeproof vinyl flooring. The floor in my bathroom and hallway are two different heights. The hallways is 1/4 inche shorter. I was planning to use underlayment to bring the hallways height up. The instructions say not to use underlayment with Lifeproof, but is there actual reason I can't? It voids the warranty, but I actually bought the material at auction, so it's not under warranty anyway. Will underlayment work or should I use something else?