Another put in option is to fly into Puntilla Lake and coordinate with Rainy Pass Lodge to take you down to the river on horseback. It’s a full day of effort to pack and trudge your gear the 1-2 miles down a horse trail to the river, and a lot more work than just flying into Sheep Lake. I might just mention that it’s been done, is possible, but a lot of work. I guess it makes sense if you want to spend a couple days at a lodge before beginning your float trip.