Actually, if I were you I wouldn't suddenly start disliking the cars for that reason. Except for the windows being too tall like I mentioned, the Rivarossi coach is a pretty accurate model.
It's based on one of several types of 44-seat coaches built for UP by Pullman, ACF, and St. Louis. Their step traps folded up such that the visible edge blended right into the car's side sill. You should be able to see a ledge under the door about 6 scale inches up from the bottom of the side - that's the visible edge of the trap door, and below that is the folding trap itself.
Admittedly this looks a little weird compared to other Pullman and Budd cars, but it's correct. Here
is a photo showing one of those cars (in Amtrak colors) with its door and trap open. If you wanted your cars to be able to serve low and high-level platforms, you could add the steps and then cut away the 6" or so of the side sill that represents the steps in the closed position.