I don't have NYGM mod on my computer; check that mod to see when the equipment, bases and subs become available. They are supposed to be historically accurate. However, the mod requires a three month in base timeline to obtain. You could probably thwart this via SH3CMDR.
Changing the GWX files to accomplish what you are trying to do would require a lot of work, probably on flotilla, configuration and campaign files.
I think the only ones who could answer your question (on the GWX team) would be BBW or Privateer. I don't have enough knowledge or computer skills to be helpful.