Here is what I came up and successfully tested :
1) The Gunderson Well Car
Only 3 copies of the GundersonTwinStackA, GundersonTwinStackB and GundersonTwinStackCDE need to duplicated, in folders : GundersonTS-double, GundersonTS-single and GundersonTS-varia.
All data concerning the various containers are located in the Cargo folder, as such:
2)Cargo
So far I have 4 specific folders to house 1) the container .bin file and 2) the container model .geopcdx file; all texture file re. containers are in the Textures sub-folder

Note, in the «Container_Buzz» are the newly repainted containers created by Buzz...
in the «Container_Gtrax» are all the 20 double-containers from the Articulated-well car created by Ricksan (permission granted for this redistribution)
in the «Containers_QcRail» will be other containers not included in the other two collections.

I have created a new way to maximize the container permutation for added variety; thus going back to the «GundersonTS-single», each well car has 2 options : 1) a container automatically visible when placed in the scenario as a «child object» and the 2) option places a second container via the «cargo option» (when a thick mark is invoked for loading). Thus, same well car with 2 containers option. Furthermore, I use the «GundersonTS-double» folder for twin-stack of the same livery.

Hope my 2 screengrabs will convey my idea:
1. The Child object at the make-up stage of the consist
2. The Cargo optional version as the load parameter is ticked
Note : I repainted the default container onto MSC
... Now we are opened for your input

P.S. Have a nice Thankgiving

QcRail