Something like this maybe:
ECML station, bridge, tunnel. I made the bridge straight for easier construction.
Track all on one level but the scenery rises and falls all around. This is simpler and more reliable than trying to create gradients in the track.
R2 and R3 radius curves are used but are hidden. Elsewhere min radius is approx 610mm.
The only turnouts that have to be Setrack are the optional facing crossover under the hill within the R2/R3 curves. Everything else is Streamline and If that crossover is omitted you can use Code 75 if required.
Streamline: 5 curved right, 5 curved left, 1 large Y, 2 medium left, 1 medium right.
The only place where the twin track has the normal Streamline spacing is over the bridge and in the fiddle yard.
Basic fiddle yard in the form of two passing loops where you can manually set up one train while another is running on either circuit.
There is a facing crossover on the left hand side. That is as per the prototype.
It's still a bit rough and some details would need to be worked out to turn it into a working layout.
The track gets close to the backscene in places so the scenic edges could be difficult to disguise but that's pretty much unavoidable in such a small space.
The operation would have to be checked. I know that some wrong-road running is needed to exit the inner FY loops in the clockwise direction (and enter the outer loops anti-clockwise) but that might not matter if the layout is more about play value?