Hey, I used to live in Lodon Bridge Acres, a neighborhood developed in the 60s across, and north east Kirk Lake. I lived there from 1963 to 1976.
When I lived there, there was a turnstile clearing on Stocum Ave; it was on the right side of the road (when coming from Hill St.), at the top of the hill. From there, tracks extended left (crossing Stocum Ave) and curved to run (sort-of) parallel to Stocum Ave back toward Hill St. Three houses now sit on the trackbed, but in the 70s it was visible, and only about 30 ft from the road.
Directly at the Hill St./Stocum intersection stood the house of a friend of mine, and next to it there was a level dirt road that curved left (south) to a house at the border of the Country Club. Given its location, I believe that this road originally was an extension of trackbed, possibly where filled mine cars would sit.
On the other side of the turnstile, the tracks went South along Kirk Lake. When I lived there, there were 8 hay fields along the span of Hill St from Stocum Ave to North Lane, divided by stone walls. Behind these fields were woods sloping down to the lake shore, and in those woods the trackbed ran. I believe that after the tracks were abandoned in the 30s, fields and woods I'm describing became Camp Mahopac (btw, if anyone has pics or info about this camp I'd love to hear from you by email.) Anyway, as kids my brothers and I discovered the ruins of many camp cabins and even a "main lodge" building there.
The property has since been developed into upscale houses on three roads Kayla Ln, Kaitlin Rd and Tyler Ct. The trackbed ran in the woods between their back yards and the lake shore. Part of it is still visbible on Google Maps paralleling the very last stretch of Tyler Ct (where it stops at a cul-de-sac.) You can also see where the trackbed crosses a very long driveway off that cul-de-sac.
Continuing south, I believe the trackbed became what is now Lakeshore Dr, and made up one segment of Out of the Woods Ln before it crossed 6N. Hope that helps.