Dave Dye has been kind enough to give me a copy of his work on the 3 Silverton railroads and I have just now started looking at them. My scaling of the D&RG track past the end of the SG&N engine house is about 450' into the Stanley Placer, a parcel that exists to this day largely undeveloped. The maps are dated 1920, so some things had changed prior to this mapping effort. The SG&N engine house facilities are the current location of the A&B Camper Park.
What is really fascinating on the Silverton Railway is the existence of a large reversing loop in Chatanooga that I have not been aware of. By 1920, there was still some traffic from the Silver Ledge mine at that location. The line continues to the wye at Red Mountain Town, but nothing past Red Mountain Town. Grades on the north side of Red Mountain reached 5.1% at one point, and were up to 4.7% and 4.8% on either side of Red Mountain.