Not really mod related, just an observation.
If you were able to make this mod without (I presume) writing large swathes of custom code, that means that GTAV already has some kind of provision for controlling trains. So why didn't they implement it for the vanilla game?
Right now ENT and TrainerV and really any other trainer spawns a car, but I have to drive it to a location. Is there a mod that's the equivalent of FSX's slew mode? Where I can "pick up" my cars and move them around without driving?