One end at the metal gate S of Barcroft station and the other end at the fire ring/parking spot at the Trail Canyon/Queen Canyon Saddle. From S to N: Up the road to White Mountain Peak, then cross country north of there. Through the cross-country leg, stay on the crest-top plateau and ridgeline to Montgomery and finally over Boundary Peak to its informal trail down to the Queen Canyon access. ~30 miles. Very long drive for the shuttle.
Closer to 30 miles than 50. The true traverse goes Queen Canyon Saddle to Highway 168, or the bottom of Black Canyon.
Which is actually 50 plus miles.