It's a section of the state where roadways and trails can be exceedingly difficult to maintain in good, operable condition. The primary, heavily-engineered highways themselves are tough to keep operating even from one year to the next, weather depending. Whole hillsides sliding off to the river valley below, and so forth.
Might take a lot to make it travel-worthy. Might take quite a bit, long term, just to cover all the repairs that such a trail is all but certain to entail.
Nice way to get north or south, though, off the main highway. If zero motorized vehicles, or at least zero passenger cars/trucks, it could be about the only safe way to get north or south aside from the main road.
Interesting project.