Grand Canyon National Park recently updated their noncommercial river trip regulations. The new regulations are dated March 9, 2017. River runners are required by the Park to have a printed copy of the regulations with them at all times. They can be viewed at this link:
Included in the new regulations is language GCPBA discussed with the Park about stow away motors once again being allowed to be carried on trips, for use only below Separation Canyon.
The trip will not be classified as a motor or hybrid trip. The regular maximum non-motorized, noncommercial oar trip lengths will apply.
You can read about GCPBA's announcement of stow away motors being allowed again here: