Right, it would be awesome if one could simply point to a path of another installed component and use order of the paths to sort priority - like in rfactor(1)
Are you referring to being able to Group tracks? Like a trackpack could be under its own heading in the track list? (as in rf1). I asked for that more than a year ago. It would be grand.
In rFactor 1 I could race against you at, for eg. Silverstone, yet you may have original textures installed in your Silverstone, while i may have "SLN's Silverstone Texture Mod" installed on my Silverstone, while someone else may have "John Smith's Updated Billboards, Grass, and Sky for Silverstone" mod installed. Basically, certain mods that don't affect physics in any way shape or form, like for eg. texture mods, don't cause mismatches online with others who don't have those exact same mods installed.
That is a bit dangerous though with regards to cheating. I'm not going to details but my league had one driver using such track-related simple file replacement for cheat purpose and no mismatch. Obviously in rF2 this is not possible thanks to packaging which checks for each modified bit.
In Nascar Racing 2003 on GTP endurance races, some people had the "day" version textures of tracks on the packaged supposed to be "night," and like in the example listed above it didn't affect any aspect of the simulation except for the visibility - which was a big gain.