So I got back from a trip a couple weeks ago where I took my 7D, 70-200 II, and 10-22 lens. I was hiking with a 65L backpacking pack, but I wanted to have easy access to my equipment without taking the pack off and missing opportunities and wasting time. I ended up getting a Lowepro Toploader Pro 75 AW II, which fits my 7D and 70-200 with the hood reversed. It will fit the camera with a battery grip on it too, but I didn't take that extra weight. The bag is designed to be used in a bunch of different configurations, so there are 4 attachment points on it. The strap system that comes with it was heavy and redundant when I already was carrying a backpack, so I used some paracord and lightweight S-biners to attach the upper two attachment points to the shoulder straps of my backpack, and two more on the lower attachment points and then to my hip belt to stabilize it. Weight of the camera bag without any straps is 680g, and another 20g for the strap system I made. The camera bag also has a built in rain cover which was pretty nice, and I kept the bottom portion of it on for the whole trip and didn't worry about setting the camera bag down in damp areas or splashing water on it. I also had my 10-22 lens in a Lowepro 9x13cm lens case attached to my hip belt so I could easily do lens changes.
Overall I was really happy with this solution. It was quick to access, carried great attached to the pack, is very well made and durable, and carried all my gear. At the start of the trip I was worried I would regret bringing the really heavy 70-200 f2.8 IS II, and wasn't sure the $100 for the camera bag was worth it, but turns out I had nothing to be worried about! Any other backpackers on here that bring their photo gear with them when they go?