I going to be doing this as my breather system is fitted in my battery tray now. I don't like the idea of a live cable running from back to front under the carpet. If it rubs through it will dead short and set fire to the carpet. Problem you have is it will need to be a large fuse because of the starter amp draw other wise it will keep blowing. The problem is with a large fuse and a good size live cable is you could have a small short that's not going to blow the fuse but could still get hot enough to set fire to the carpet! I'm just going to get a good quality cable and run it inside a flexi wire conduit