When my son and I did a 50 miler a few years ago, I contacted the NFS local office beforehand. We were traveling through the Teton Wilderness, near the headwaters of the Snake River and the Continental Divide. Two days in, there was a backcountry ranger living in a log cabin. As fate would have it, it was due for a fresh coat of shellac that summer. The forest service arranged to have several gallons of shellac packed in by horse, and my son and I spent a day applying it. We finished a bit early, and we helped fell some trees for the ranger, who was building a rope corral next to the cabin. The next morning, the ranger made us a pancake breakfast before sending us on our way.
So contact the land manager and ask if he has any ideas. If you're doing work at or near the trailhead, he'll probably supply the tools.