I have not heard of a currently manufactured combine car with lights at the rear. Weaver's 60' baggage car is nice, but no comfort facilities for passengers or crew. Let me propose a project and please poke holes in it, no sense making the same mistakes again and again.
I would start with two K-Line(or two Williams, or two MTH, or two Lionel) cars, one observation car with marker lamps and one baggage car. First generation K-Line cars with lights on the floor, not StreamLighting. Williams and MTH baggage cars are interchangeable for this project. Remove the observation car's body from the floor and preserve the wiring to the marker lamps. Rotate the body 180 degrees so the B end is now at the rear of the floor. Cut the body to a length so the baggage car cut will be between the doors. Cut the baggage car to a length so when joined to the B end of the observation car it is the length of the floor. Plastic Weld those two main pieces together, sand, and paint. Jury rig (bash) the marker lamps to the B end of the observation car and connect the wires. Put the new body on the floor, one of the center screws may not line up with the pillar in the body but the corner screws ought to be lined up. No need to remove the trucks or modify the light sockets in the floor.
What's wrong with the plan? What am I overlooking?
Thanks, John in Lansing, ILL