The vents, awnings and AC units on the top are definitely giveaways that a van might be an RV.
Since we're talking stealth B camping, I've sometimes had idle curiosity when looking a newer models about how "stealthy" the newer Sprinters actually would be since Mercedes designed the grill with quite a large logo.
There are after-market conversion kits for older Sprinters with Dodge or Freightliner (like ours) grills (with the Mercedes engine), but we passed on that option, because I suspected the big "star" logo might make the van more of a target for unwelcome attention.