Drove in at the last minute, the sign says full, but talked to backcountry office ranger and he got us a site right in the middle of mather. Elk everywhere, huge site, with fire pit and picnic table.  Flat tent pad, under a tree. and a lot quieter than I thought it would be.  We were headed down to Phantom ranch the next day super early and was within 10 minutes of backcountry office on the south rim.