Could only get one night at the Mather CG in Grand Canyon, so we went boondocking just outside of the National Park in Kaibab NF. It was only a few minute drive from the park entrance, and had nearby access to shops.
This is a primitive campsite so no facilities, bathrooms, water, and pack in pack out. There were a handful of campers here but enough space along the road to find a private spot. There were a few other nearby forest roads that offered dispersed camping but this one had fewer people.
Would certainly camp here again if we can't get a spot in the park.