I should add a few more things that aren't obvious from the photos. This isn't a National Park, National Forest or National Monument. Not even a State Park of State Forest. It's BLM land that's a minimum of 25 miles from the nearest paved road, so really, few tourists even know the place is there - which makes it rather attractive to me.
You can camp anywhere on BLM land that camping isn't expressly prohibited (a miniscule percentage of places). The only access into the Little Grand Canyon is from one trailhead at either end. Our trailhead parking had only two other cars parked there upon our arrival mid-morning on Saturday, and there was only one other vehicle there when we left at mid-day on Sunday. On Saturday we encountered only two parties of day hikers (two each, and both were not far into the canyon), plus the pictured pair of canoeists floating downstream past our camp. On Sunday we only encountered one overnight party of two hikers who passed our camp heading downcanyon as we were breaking camp ourselves, and one pair of dayhikers heading in as we were heading out.
That's it.
Ironically, this is nonetheless one of the more popular areas of the Swell. When camping I prize my solitude.