The width of the 609, proprotor tip to proprotor tip, is 60 feet (hence the 'D' value). Pilots have a good visual of the stiff proprotor blades which are about 15 feet above the deck causing no hazard to persons walking on the deck and of course there is no tail rotor to walk into. The length of the 609 is 44 feet.
In comparison our Bell 212s have a 'D' value of 57 feet 3in from the forward tip of the main rotor disk to the aft tip of the tail rotor disk. The pilots cannot see the the tailrotor while maneuvering which is about 5ft 9in above the deck when sitting on the skids.
So no problem for the 609 operating to typical rigs and platforms. Many helidecks are sized for the old S-61.