I backpack with mine extensively. I use an Rm3di with a Rodenstock 32mm, and I carry a Contax 645 with a 120mm. Yes, I'm a glutton for punishment. I use a Lowepro Mountaineer backpack, then I went to a sporting goods store, and got a cloth tackle box case that was just big enough. I then bought some high density foam (make sure you get the kind that doesn't disintigrate!), made the appropriate cutouts for the back, knobs & such, then covered the foam with a nice felt liner. The camera is fully supported & cushioned and the whole thing is very lightweight. The case is held in place high in the backpack with the standard supports that come with the pack. Have used it for about a year now and very happy with the setup, but a bit time consuming to put together. I can email you a photo if you are interested.
As an aside, if you carry a lot of weight, I highly recommend using hiking poles. Ascents are not too bad without them, but descents on steep terrain & on slick rock are brutal on the body over time and the hiking poles really take the brutality out of the impacts. As you might expect, this necessitates mounting your tripod on the pack.
Hope this helps.