John, I think your best method for laying this out is to install the 4 way where it’s going to go. Leave your present yard tracks in place. Connect everything up using flextrack. The problem now is hooking the track together with pins. It can be done. Gargraves makes something that may help. They are flat pieces of metal that will insert in the web of the rail and rest on the roadbed. Rather than trying to connect the track together using the pins and distorting it all over the place. You just slide the last tie back a bit and the flex section of track and it just drops over the Gargraves strips as the rail spreads open. Once it’s on you can slide the tie back in place. You could probably substitute some thin brass stock. If your worried about electrical continuity. You can solder small jumpers to the rails.
I’ve done this a few times making track changes to a ballasted pike. I usually use the brass strips and solder them into one set of rails. I think the Gargraves ones maybe stainless. In your case. Maybe the do it to four way before it’s on the layout. Pins will be used to your station tracks and then you can drop the rails in place on your 4 way. Just leave the rails slightly long and keep test fitting and filing it till it fits right.
By the way. That’s a great looking scene.
