Choosing which assets to use

I think I'm about to abandon a preconceived notion.
In the unlikely event I complete this route I'm starting to a level where I feel comfortable releasing it (here), I was attempting to NOT use payware assets. However this was based on what I now believe is a faulty assumption. I am now realizing that with the exception of the "kuju" folder, everyone out there has different routes/assets (even if ALL they every bought was the basic game) based on what years they bought the game.
So there is very little content (well USA content anyway) that everyone has from "Kuju/RailworksUS", which helps explain why almost every route out there has some payware route it depends on...
So, which "Object Sets" are safe to assume everyone has?
Just "Kuju"? Or are there others? Is it true (as is claimed on wikipedia) that if you buy TS2016 and have NEVER bought any previous versions the only route you get is Sherman Hill?
In the unlikely event I complete this route I'm starting to a level where I feel comfortable releasing it (here), I was attempting to NOT use payware assets. However this was based on what I now believe is a faulty assumption. I am now realizing that with the exception of the "kuju" folder, everyone out there has different routes/assets (even if ALL they every bought was the basic game) based on what years they bought the game.
So there is very little content (well USA content anyway) that everyone has from "Kuju/RailworksUS", which helps explain why almost every route out there has some payware route it depends on...
So, which "Object Sets" are safe to assume everyone has?
Just "Kuju"? Or are there others? Is it true (as is claimed on wikipedia) that if you buy TS2016 and have NEVER bought any previous versions the only route you get is Sherman Hill?