One more thought to the idea of finishing interior van walls: If you are in an area where road salt is used, you may want to have your van's body oil-sprayed for rust prevention. I was getting a quote from an oil-spray place recently, and they mentioned that it would be easy to spray into my E-350 hollow wall cavities, because the interior of my van, is the factory bare-bones version. They also commented on the difficulty that they sometimes encounter in vans with completely finished interiors. Their suggestion for people who plan to cover their walls, is to panel the interior in a way that would still allow access to the bottom of the walls, via removable panels. Then when it's time to oil-spray, they can reach the areas where they want to go.