There is a trail that runs just above the inner gorge for part of it, but the only way you can see the entire canyon is from the river. There are very few trails that actually reach the river from the rim and as a hiker you can only access less than 1% of the shoreline of the river. There are several books describing hikes from the river listing more than 100 hikes. But most of these follow creeks up side canyons that ultimately end at an impassible cliff that may have a waterfall if you happen to get there after a rare rainstorm on the plateau. See the Park Service website for more info on hiking in the Canyon: http://www.nps.gov/grca/planyourvisit/backcountry.htm .

I think your project ( http://360extremes.com/ ) is cool and quite ambitious. Given the huge logistics of a Grand Canyon rafting expedition, I can’t imagine putting that into a polar circumnavigation trip. Just getting a permit could be enough challenge. That is done by lottery. But don’t let any of that stop you. If I were doing a Canyon trip with a launch date that fit your itinerary and you wanted to join my permit, I would certainly welcome you.