I had no choice, just bought a new vito which has a 15mm wood/plastic type floor. Had the sides ply lined but not the arches. I think as long as you seal the gaps properly it will at least help with any spillage. In fairness in my van at the moment i only get a few drips of water from the hoses, its not like your going to get buckets of water on the floor everyday, unless you have a problem when filling or a seriously leaking tank.