there two option to make the train longer
1. Reduce the capacity o your waggons
2. or use this midifikation
But I have now an other question .
I our forum ( train-fever.net) is some of modder they build american locomotive and now I see amercian waggons in your screenshot.( iron and coal/container waggons)
Did you build it on your own ? I would be happy to see you maybe in our forum
A really nice thankyou beforehand for your answer.