I'm assuming this is the hatch:
That doesn't really look too comfortable to crawl into, and most of the time it was covered by the Skins banner. I'm not sure what the advantage would be to stowing away in the hatch vs. just standing in the side doorway.
It looks the hatch is where they stash the bike: https://www.facebook.com/marathonmanuk/photos/a.1006961546054770.1073741835.612632838820978/1018137211603870/?type=3&theater
So presumably the photo showing Rob running from behind while the RV is in front of him with the hatch open, is taken by Dustin riding the bike behind him.