The best thing about 9 Mile Canyon is that it's 40 miles long.
You should be able to loop back through Whitmore Park, Minnie Maud Creek, or Argyle Road. The road is level dirt.
If you pick a good spot, and have time to explore, you may find petroglyphs, pictograph, pithouse dwellings, and other ruins from the Fremont Indians. I was half-asleep the whole way back, so I missed a lot.