I have used Lock and Lock food storage boxes for camera storage in my pack. I wouldn't want to guaranty one against full immersion with expensive gear, but I'm confident about rain and dust protection. They make long ones for pasta storage that you might be able to use for long lens storage. The small round ones definitely work for short lenses. They are the lightest option I have found for hard-sided waterproof containers.
For basic protection the Zing line of camera covers are light and protect against bumps. I have used a Zing cover on my camera along with a Lock and Lock box. Domke makes some simple padded wraps that will protect anything.
But the problem I have with hauling a DSLR is deciding whether to keep in im my pack, or out where I can rap off a shot without having to stop, unload, shoot and pack it up again. It is an easier decision on a day hike and good weather. There are lots of chest pack arrangements that use top-loader camera bags--- Lowepro makes a bunch. Some come with harnesses and most have D-rings that you can make quick connects to your backpack shoulder straps, which also takes the weight off your neck. Quick attach buckles can be snapped onto the slider webbing for a sternum strap, and then used with a side release buckle and snap hooks. The top loader bags can be used for storage in your pack or carried "up front" as conditions and your needs permit. Bouncing is proportional to the amount of hardware and connections you can tolerate.
OP/TECH USA makes this arrangment to go directly to the camera, but it could be adapted to a top loader bag with D-rings. It will bounce.