So close, yet so far (SOLVED)
TL;DR - I ran a train :D
Following up on So close, yet so far...
I took this as an opportunity to apply the techniques in Satisfactory 1.0 Tutorial: Easy Point & Shoot Smooth Railways Anywhere to extend my rail line, and connected the coal nodes I was interested in with my existing rail line running along the coast.
Video is the initial test run of the line after I setting it up. I'm pretty happy with the result!
TODO: smooth out some wiggles and a corner that's sharper than it needs to be, remove all the guide beams, add signals, and actually start moving the coal.
Sometimes a project isn't as big as it looks when you're staring at the map.