Have just got my, '101 Track Plans' by Linn H. Westcott out and flicked through it for you. Not sure what your space allocation is. But what about Plan 100 page 68, 'Ohio Central System'. Or Plan 92, page 59, Missouri-Kansa-Texas? Hell even make it modular if you like.
The reason why I suggest these two, is that, in all my years, i have never seen a UK layout based on a wye. I thought about a few years back, but even the minimal single track formation takes some space.
What are your thoughts on this type of design?