The panel truck seats are different from pickup and suburban seats. A one-person driver's seat was standard - its top/back folded forward and came on its own base. The passenger seat was an option and it folded/tipped forward as described above (and had a base as part of the seat assembly). With these two seats in place is is still possible to get into the back from the front seat area and via the passenger door.
There were no 47-55 1-ton Suburbans.
Here are illustrations of the driver'side Panel Truck seat-assembly. Here is the passenger's-side seat (note the hinge at the front of the seat-base, at the floor).
Here are the floor covers that go under the Panel Truck front seats. 
