The trains use to follow the San Juan River through the valley, before the 28 mi long lake was created in 1965. The railroad was used to take supplies down to help build the dam near Farmington, NM. The the tracks were taken out as the lake filled. The railroad that wound its way through the Jicarilla Apache and Southern Ute reservations was abandoned; and very quickly was dismantled–erased from the land.
Board @ Mt. P: Ride to Denver; rent a car and drive beautiful Hwy 285 through central Colorado, south across South Park, San Luis Valley, towards Wolf Creek Pass, where you cross the Continental Divide again.
Pagosa Springs is the last of the good cell phone contact, grocery store of any kind and general city services. Another 45 minutes west then south, puts you at Navajo State Park, your terra firma destination.
Board @ Ft. Madison: Ride through Kansas City, Newton, KS, La Junta, CO then southwest to Santa Fe, NM. Rent a car and drive north through Abiquiu, to Chama, NM. Keep going up to Pagosa Springs then, west and down to Navajo Lake. OR drive from Santa Fe to Farmington, drive up on the west side of the lake to the north end, at Navajo State Park.