I used to have a Pathfinder, and I found a way to sleep in the back of it, making use of only 'the parts that came with the truck', and I can do the same thing with the X, as outlined below:
0)
With the passenger side rear seat folded down:
there isn't enough length for me to sleep in the back. I use a Therm-a-Rest camping mattress that is 20.5 inches wide and 73 inches long:
More room can be created by removing the passenger side rear seat cushion, however that creates an empty area between the cargo area floor and the passenger front seat.
1)
Flip the passenger side rear seat cushion up, lift up on the plastic latch handles (e.g. upper handle in this photo), and remove the seat cushion
2)
Raise the passenger side rear headrest to it's upper position, press in on the release button, and remove the headrest
3)
Either tilt the passenger side front seatback forward, or if possible fold it flat, and slide the passenger side front seat forward
4)
Place the headrest on the floor on the passenger side rear. The side of the headrest that goes against the person's head goes against the floor, so either make sure the floor is clean, or protect the headrest
5)
Place the passenger side rear seatcushion with its rear edge against the rear edge of the passenger side front seat
6)
Push the passenger side rear seatcushion's front edge down so that it rests on the headrest. This leaves the seatcushion level with the cargo area
7)
There is now a fully supported area that is actually a bit longer than my 73 inch mattress
0)
With the passenger side rear seat folded down:
there isn't enough length for me to sleep in the back. I use a Therm-a-Rest camping mattress that is 20.5 inches wide and 73 inches long:
More room can be created by removing the passenger side rear seat cushion, however that creates an empty area between the cargo area floor and the passenger front seat.
1)
Flip the passenger side rear seat cushion up, lift up on the plastic latch handles (e.g. upper handle in this photo), and remove the seat cushion
2)
Raise the passenger side rear headrest to it's upper position, press in on the release button, and remove the headrest
3)
Either tilt the passenger side front seatback forward, or if possible fold it flat, and slide the passenger side front seat forward
4)
Place the headrest on the floor on the passenger side rear. The side of the headrest that goes against the person's head goes against the floor, so either make sure the floor is clean, or protect the headrest
5)
Place the passenger side rear seatcushion with its rear edge against the rear edge of the passenger side front seat
6)
Push the passenger side rear seatcushion's front edge down so that it rests on the headrest. This leaves the seatcushion level with the cargo area
7)
There is now a fully supported area that is actually a bit longer than my 73 inch mattress