Dsquarewd: yeah, it should be no problem. It is off the beaten path enough that no one will bother you. You can pitch down behind the trees (cove / Colorado is hidden from you) Nice place. Especially up on the shelf / next to the river proper.
I did just look on both the NPS site and desertusa concerning primitive camping. Both say vehicles are restricted to designated areas in the backcountry...and boats can pull up pretty much anywhere along the shoreline that isn't restricted and camp (wth?). So, a bit of research or calling the NPS concerning a map of authorized vehicle primitive camping locations may be in order. Or not. Nice canyon though.