Hallo Mona,
ganz so schlimm est es mit der Höhe nun doch nicht. Der South Rim liegt etwa 2.200 m hoch. Der North Rim liegt ca. 500 m höher.
Hier dazu ein Info aus Map'n'Go. Danach liegt der Campground am South Rim auf 6.720 ft.:
Mather Campground
Rates Subject to Change
3/1-5/31 Ev day $12.00
6/1-8/31 Ev day $15.00
9/1-11/30 Ev day $12.00
Public. National Park Service. PHONE: 520-638-7888; 800-365-2267. LOCATION: Grand Canyon National Park, Arizona 86023. South Rim Village, 0.5 mi from rim. Restaurant and lounge. TERMS: pets allowed, check-in after noon, check-out by noon, reservations required, seven day maximum stay, Rental Reservations 3/1-11/30. FACILITY: 320 total sites, 320 RV/tent sites, altitude 6720 ft, no drinking water, hot showers available, flush toilets available, fixed dump station. SERVICES: guest laundry (fee), propane, groceries. OPEN: Mar 1-Nov 30.