But there is apparently OLE in October 24 as far as this odd cripple sidings/loco cupboard (the big grey bridge in this image is the footbridge adjacent to Kent Avenue): Which suggests 90s worked beyond Ripple Lane but not all the way into the sidings
There is definitely no OLE into the Ford terminal. It stops about two loco lengths beyond the loco slip. The manner of shunting for AC arrivals is exactly as you described. For departures it's either as you suggested (the pilot hauls the wagons out) or the pilot will propel the wagons out then the mainline loco attaches between the Ford gates and loco slip. In your first picture where the points diverge to the right is where the GB pilot used to be stored when not in use (just squeeze in between the arrival/departure line and the FORD shunting line.
I didn't know that GBRF were using a class 08 at Dagenham when 92s were hauling the car trains, but managed to find a snap here of a 92 + 08 in the loco siding, taken in 2020:
https://www.flickr.com/photos/186859825@N04/49614736078/ (Photo: Daniel Warman)
When DB were using a 90 on the car trains to Mossend, there was a class 66 pilot based at Dagenham which was used to trip the Transfesa traffic (from Spain) from Ripple Lane Exchange Sidings into Dagenham, and also across to Barking container terminal. It must have been used to take the car wagons into the Dagenham Ford reception sidings too. The groundstaff cabin was located by the loco siding so it was a convenient place to stable the pilot loco. A 66 is seen in the loco siding with a 90 alongside in 2018:
https://www.flickr.com/photos/37271_37418/46524975651/ (Photo: Transport 37418)
The general layout is seen more clearly here, with the line into Dagenham ARC (Heidelberg sand loading and stone offload) diverging right:
https://www.flickr.com/photos/linesidesoutheast/39735290693/ (Photo: Anthony Kay)
A class 90 is seen on 6X77 between Dagenham Ford and Ripple Lane Exchange sidings in 2018:
https://www.flickr.com/photos/tunnel_one/31260071538/ (Photo: Antony Kay)
On google maps you can see the gate across the line marking the entry into the Fords sidings - it's just east of that loco siding and just west of Kent Avenue. The OLE appears to stop just short of that gate. Due to the length of the car trains, the reception sidings extend all the way to Marsh Way bridge - on Streetview from this bridge you can see loaded double-deck car wagons waiting to be collected from the reception sidings. My understanding is that DB left the wagons here (or collected them) and they were shunted into the Fords complex itself by the company's own internal shunt locos. These were / are 0-4-0 machines which look too small to comfortably move an entire car train by itself, especially around the sharp curves of the site. There's some brief glimpses of internal shunting and car loading at Dagenham in a short promotional video included in
this post in the thread of industrial systems.
To return to the topic of class 99s, they would be ideal for the car flows as you get the benefit of electric haulage for the trunk haul, but they can also take the wagons into the Dagenham Ford reception sidings off the wires.
4Q91 has now left Doncaster Down Decoy, heading for Peterborough with 99001 and the same consist as 4Q90...
