I'm not really good at programming mods but I started to customize LTN so that at least some of the functions are given. I got it so that I can send trains with gauge cars to a station and if there is no train with the right number of cars in the depot then a shunting locomotive can pick up and deliver cars.
but i don't trust myself to reprogram this to a mod of my own. but if you can create a mod with the changes in LTN i can pass them on to you.