Hy Dufrene, I have a half-baked 24h Le Mans version but I have never finished. Maybe someone with time for it would like to take from current state. All in all there is a 24h version out there, not sure how accurate it is but seems to be functional. Actually the modding system seems to be changed a lot from this track building era, Max 2010 plugins support (my version) seems to be discontinued and they buried gJED, which was not perfect but it used to be very handy.
Also, a number of shaders and track technologies has changed without proper documentation, so the modding process is more than the hard work of modelling and texturing, the main part of labour is trying and error guessing how the things in-game work. Very tireless.
I'm currently creating airports and scenery for X-Plane 11, it would be very fruitful if S397 staff have a look on how Laminar Research put their modding system together. If rFactor2 had a similar system I'd be happy to come to rF2 modding back. In addition, their shaders are OpenGL readable and achieve amazing visual results with good FPS (flight sim deal with much more polygons then race sims), it's also worth to have a look inside.
rF2 needs to modernize, at least to provide a decent WYSIWYG editor with the same in-game shaders being updated by Steam at same step when the main game core is also updated, if they really intend to have a fraction of mods that rF1 use to have. The DX11 Scene viewer is a bad band-aid. I fell a bit sad seeing the new S397 DLC excellent content as the newer GT3 car competitors pack being used in a dated and confusing GFX engine. I can't barely imagine how that content would perform in Unreal Engine for example.
Sorry, trashy English as usual.