I backpack with a DanaDesign (since bought out by K2) Terrapin X internal frame pack that fits me like a glove. IMO, a real backpacking outfit is key to successfully lugging much gear around the wilderness if you are camping. Per other's comments, I haven't seen a camera oriented pack (and I have one of the big Lowepro ones) be comfortable enough for real backpacking. I use the Lowepro for day hikes. It is better at keeping all the camera gear neat, protected and in order, but with my DanaDesign pack I can carry camera gear, food, a tent, sleeping bag etc and be comfortable (but very, very slow).
I have recently reduced my camera gear when backpacking to a single body (5DIII or 1Dx depending on photo ops - I'm likely to get a 5Ds R before my next landscape trip) and 2 lenses - the 24-70 2.8 II and the 100-400 II plus a 1.4XIII. This plus a tripod, extra batteries, filters is enough when backpacking. (Although, I'm tempted to add the 11-24 as well before my next trip.)
For access while packing in, I hang my tripod w mounted camera and lens off a large S-hook hung from a position over my right shoulder (tripod is upright and my camera at shoulder height). I can effortlessly take shots while walking w/o disengaging the tripod or take it off when needed for stability/panos etc. With this setup, I don't have to give up quick shots while carrying everything and the weight of the camera/tripod is distributed to the high-quality belt and not my shoulders. I attach a pic where my pack is the green and black one to the right. This was after a great hike around the Syncline loop at Islands in the Sky. A bit scary in places (pic 2), but I had no problems with all my gear (actually carried much more on this occasion - included the 300 2.8II for wildlife, but my sons and a friend helped w other items). I'm no hulk (old guy w the whitening beard on the left), so a good pack makes a huge difference.