Hiking in on the North Fork Buffalo Fork Trail a few miles grants access to the scenic North Fork. Hike until the trail reaches the river at Soap Creek, and put on. Stay heads-up for wood as the river flows through meadows and then small boulder rapids and eventually reaching the South Fork.
From the bridge near the confluence you can either hike up for a significantly harder section of the South Fork, or just enjoy the swift paddle out on the Class III+ Buffalo Fork.
Video: Packrafting North into main Buffalo Fork