I assume you plan on hiking through the day. If so, you're going to get a lot of harsh hard light, so you'll want to take an ND filter with you. Also a collapsible reflector would be good for fill light on any macro shots you take.
I'm not sure what the terrain is like there, but if its hilly at all pick up a set of hiking poles. You'd be surprised at how much all that gear + water is going to weigh after 6km or more, and the poles do wonders for your feet and balance. Also all that gear hanging off your body unbalances you on the more precarious areas, and the poles give you a lot more confidence with your stepping.
Another thing to consider is time. A 6 mile hike for a photographer takes considerably longer than that same hike for a hiker. There are going to be times that you don't even come close to completing the loop, or make your destination before the time you've alloted is coming to a close. Since your a photographer, this isn't a bad thing, actually its a good thing as it means that you've found a lot of subject matter.
Some tips for photographing while hiking. Depending on your location and the popularity of the trails, you're going to come across a lot of other hikers. sometimes they'll be "in your shot" or whatever and annoy you. What you need to remember or realize is that these other hikers are a photographic gold mine. Many photographers forget that adding a human element to a photograph will almost always make a photograph more interesting to other people. So don't be bothered by the other hikers, use them to your advantage.
After you've done a few hikes and become comfortable on the trail, you might want to consider over night hikes. Obviously the best landscape light is sun up and sun down, unfortunately that means if you on the trail or trail head in the dark, you might not have time to get back to the car before you simply can't see well anymore. You can take a flashlight and walk back, or you can take a tent and a few provisions, walk out to location for sundown, shoot, get ready for bed, take some night shots, then at sun up shoot again until the sun comes up and is no longer interesting, beak camp and head to the car before anyone else gets out of bed. This way you get tonnes of great light shots, evening, night and morning light, all at once. And its a very fulfilling experience.
Canon camera, Canon lenses.