Folks, I have carried several different DSLR cameras in the backcountry in summer and winter with a variety of lenses. I've shot scenics a little, but I tend to go after wildlife.
I think you want to consider something like a Lowepro Camera Case, Toploader Zoom AW 45. Now, you may need to move one size longer or one size shorter, and that depends purely on your mounted lens. With some of these, you can mount the long lens on the body, because that is what you will need when surprise wildlife shots arise. Then you can carry the shorter lens in an accessory pocket on the case.
Some things make this practical. First, you can flip the carry strap over your neck, or over neck and shoulder, or off the pack top. Secondly, it is All Weather, and I've had mine out in some pretty icky weather.
I added some velcro strap to mine for fast access, so I generally leave the top zipper undone and then just stick the strap for closure. I zip it up completely when passing through an airport. When in wildlife country, I need to have the camera out and clicking within a few seconds of eyeing the target.
I've been using one or another case like this for ten years now, and I have never had a camera damaged while within the case.