Heavy trailer following real situation or following the game balance?
The truck has only one rear axle plus a long frame wich make it a bad choice to hook up heavy trailer regarding stability while driving and i speak about real life situation.
If the frame was shorter and the hook closer to the rear axle it would be less of a problem with enough weight on it.
If a fifth wheel was on the frame it wouldn't be a problem either since it would spread the weight properly but still the frame is too long for that and there is no proper trailer in the game yet for that kind of use.
F750 with a frame configuration who could hook up to the current trailer and still being consistent and considered ok to drive.
Even those don't have a hook their frame.