Gordon, at this point, I’d be very tempted to free lance the distributor. There are any number of great kits available to model the time period involved. It’s your railroad, you call the shots.
I’m fairly familiar with the various “Standard Oils”, and a few of the smaller major oil companies. For the time period you are modeling, I urge you to go freelance or model the prototype from a picture as best you can. During this time, the major oil companies had few standards (no pun intended) for their distributors/wholesalers/dealers that related to facilities - other than signage. Local laws (if any) would be adhered to for safety purposes (like tankage placement, berms, safety ladders, etc.).
The largest tanks you would normally see would be about 40 foot high, maybe 20 foot diameter, but this could vary a lot. Horizontal tanks were also common too. While there may have been some welded tanks, I believe most of them were riveted.
Traffic was essentially (but not exclusively) tank cars coming in, and trucks going out. While meters were used a lot, scales were also in use. My opinion is folks trusted the scales more than the meters.
Having spent over 40 years at various refineries and terminals, I certainly wanted an oil facility on my HO layout, and ended up modeling a generic terminal. A refinery would have been nice, but IMHO, to do one justice, it would take up a whole lot of space.
I think generally it worked the other way around - that is, rather than Standard Oil buying land, building a distribution site, assigning employees to work there etc., it would be more like local boy Joe Smith would set up Joe Smith Fuel Oil Co. in a town, and would then contract with one (or more) major oil company to be the distributor for his town or area. So I don’t think you’d see any kind of standardized (no pun intended) plan to an oil distributor.
BTW there’s an oil / petroleum distribution company I go by once in a while in Bloomington MN that’s served by Progressive Rail. There is a small office building and an oil loading rack, plus a small pipe set up for unloading tank cars. Otherwise it’s a small vacant lot; the tanks are (I assume) all underground. Would be pretty easy to model !!