It needs a ramp and or big sliding cargo door.
That would be nice to have, but not likely because of difficulties that would be encountered with the pressure vessel (the V-22 is not pressurized, the 609 is).
The 609 prototypes have the old 707 style door installed that opens forward, but a design for a Lear-style clam shell door was completed years ago and was under serious discussion as the most likely production fit last time I heard (that also had winch configuration capability designed into it). There was also a wider cargo door design (not sliding) that will likely be an option.
Of course there is the emergency egress door on top of the fuselage for water exits etc. And external to future production models the first prototype (not sure about the second) has a 'blow-out manhole' in the cabin floor with explosive charges for the test pilots to have access to, but fortunately it has never been needed.