I was thinking that as well, although the idea of accurately placing gantries all the way along the route is one which I'm not too keen on - particularly when you think that you'd also need to create custom objects such as the Crossrail tunnel portals at Paddington and the new Reading station. One for Keith or Just Trains maybe?
Here's a couple of shots taken during a run from Windsor & Eton Central to Slough, the track just needs signalling and one or two gradients smoothing out and then I can really start on the scenery, which for now is pretty basic (excuse the decals which I quite honestly just couldn't be bothered to hide

).
Ready to depart at Windsor & Eton Central...
The view from the trackside walkway
Heading out over Windsor and towards the Thames...
...where narrowboats are moored for luncheon
Past Eton College Golf Course
Under the A332 and M4...
And into Slough...
...where the platforms have now been extended.
JB