I don’t have any real-world examples from your era, but have a small modern facilitiy near me that unloads alcohol, and another that unloads vegetable oil.
Was it you who posted a couple of vertical tanks a month or so ago… or if not, do you remember the photo?
I’d imagine something like that set back 10 feet or so from the track. At track side would be a pipe coming up from underground with a 90 degree bend, a big valve, and some type of coupling. Hoses stored close by with mating couplings for this stand pipe and the tank car. The pipe to the tanks could be buried (easier) or run above ground on concrete pilings (more interest). You might also have a pump house, or an open air pump near the tank base.
If unloading more than one tank, multiple stand pipes / hoses feeding a manifold, that feeds the tank(s).
If you are environmentally conscious, build your storage tanks inside a concrete pit deep enough to contain the volume of the tank should it leak.