If we're talking mad ideas - at relatively low cost you could transfer the Night Riviera Sleeper there - it could then run via North Pole to the GWML.
You might even be able to transfer the 2 Caledonian Sleepers there with a bit of jiggery-pokery and reversing at North Pole.
It could become the new 'London Sleeper Terminal' - and free up early morning space in Euston and Paddington, also enabling more timely arrivals, instead of the ridiculously early London-bound times you get with the Night Riviera at the moment.
Terrific idea. Perhaps it's time to revisit the idea of sleeper services through the Channel Tunnel too, since we've got a spare terminal at Waterloo. Sleepers to the Alps, or to Barcelona?