There are some assets, including from the two awesome contributors that already responded - thanks, guys!
I am sure many have started on this, and have given up. It is just one of those tempting routes. I still haven't visited; although I live in Alaska, it isn't an easy drive out there. I would like to visit Whitehorse too. The rail no longer goes there, but the drive to Carcrross/Skagway for us passes right through Whitehorse.
Like any mountain route, working the terrain can be hard. Recent improvements in the data available gives us better terrain (in huge chunks), but the terrain and limited rail data seems to make track laying a very manual process. UTM tiles can be a pain in steep valleys. Many of the mountain peaks lie outside of the maximum draw distance even though they are just down the line a bit.
None of these problems are unique to the WP&YR. The appeal (for me) isn't unique either. I'm very much interested in the history, especially when there is a rich history to the rail, the area, and so on. I can (and will) get to take a ride on the restored and historic WP&YR. But the heyday, back when the WP&YR was pioneering some new idea called "container shipping"? That can only be seen in faded photographs and a few archived movie reels. Model and virtual railroading not only gives us a chance to recreate something from now (the beautiful tourist WP&YR), but also the chance to recreate things that are gone for ever, such as the WP&YR in the days of Steam or when Faro was a large-scale mine instead of a ghost town.
If you do make any progress on your WP&YR, please start a blog or something. I would love to see more of it in Trainz. I'm too busy with other parts of Alaska.
p.s. ben: If you ever want ideas, I am collecting every reference photo of the CR&NW I can. Around two-thirds of the 195 miles was bridges and trestles, including the Miles Glacier (Million Dollar) Bridge.