With a Rez permit, you may be able to camp on either of the two roads just north or south of the canyon off the hwy, but it appears there may be residences there to contend with.
The nearest free camping that I am aware of is just across the dam. See the geocode on this photo. I know of at least 2 other haz groups that have camped here without any problems. This within the boundaries of the Glen Canyon National Recreation Area, which allows dispersed camping. But officially
you should pay the entry fee or have an annual Parks Pass.