Keep the interior and sell it ,thats all he'll do. No idea about the business as I havent done any research but as for a catering van its perfect ,just need to cut a hole in it.
If he removes the interior look for a discount on the price. Otherwise keep the interior and offer it up here or Ebay it 8)
Playing devils advocate here: if it's a catering van you want, a transit is probably better? (I worked in festival catering for years so not talking complete b/s)