That would simply be a re-incarnation of the early 20th Century "Trolley freight" operations. Until the 1920's most of the larger traction companies ran trolley freight services, even in the big cities. The development of the motor truck killed most of these services, especially the city-based services, in the 1920's, although many interurbans provided freight service right up until WWII, and some even later. In fact, most of the larger midwestern interurbans were able to survive and keep running as long as their freight operations were viable. When these operations died, so did the interurbans.
Many of the interurbans had freight interchange locations with the then steam railroads, and some even provided power for the standard railroad freight cars as they ran over interurban trackage, though most trolley or interurban freight cars were smaller "trolley-size" cars which were more suitable to the extensive street running found on most of these systems.
Even back "in the day". however, the interurbans often battled with the local town councils over what periods of the day interurban freight trains could be operated. It seems that having eight car freight trains squeeling and winding their way through city or town streets was not the most popular situation. Because of this, many towns had a two car limit on trolley freight train lengths, except during overnight hours.