Both Hayes & Harlington and Southall are like that. The canopy, waiting room and benches are all beyond the rear of the train when it stops at the 4-6 car stop.
In the case of Southall, there is a
huge sign (just about see it in shot) in line with the inner end of the 5th car that tells people to move right down the platform, but no one does. The 5th car is also where the horizontal and vertical gap between the train and the platform is the greatest; a low platform combined with the outside of a curve on quite a cant. This means passengers are often struggling to board there, which if they'd have moved further down to the straighter part of the platform, wouldn't be an issue. Most of the time at Southall the driver has to tell people to hurry up, and to use all doors. But people will not listen, as they want to be in the rear for Ealing Broadway or Paddington. So you have almost all seats taken and several standing in the 4th and 5th coach, while at the front I can get several seats to myself.
All Up Relief platforms served by Heathrow Connect have monitors linked to the live CCTV feeds, with station staff occasionally dispatching trains too. Nothing of the sort on the Up and Down Main, where the look back method has to be used at all stations if using those lines (also the Down Relief at Southall).