We have the Galli 2 low and it connects to the rail just above the door - make sure you get the driveaway fixing kit (6x6mm) though, otherwise you'll not be able to "drive away" very easily. With the factory awning fitted, the Galli connects to the rail on the awning rather than the van - you'll still need the fitting kit.
The Galli is excellent by the way. Acres of space! Bear in mind that the interior bedrooms come separately though, so factor that cost in (think about £50 each) and the fitting kit (£25) A doddle to put up and take down, if a little bit of a faff getting back in the bag the first time we used it. The fixing kit means you can disconnect/rec