I was determined to carry my DSLR on my one week tour last year but could not find a handlebar bag and mount system (at least not one I was willing to pay for) that would work with the secondary "cross" brake levers on the bars. My solution: a Lowepro fanny pack camera bag and a cam strap. I ran the cam strap across between the front end of the drop bars, threading it through the tripod straps on the bottom of the fanny pack. This supported the bag and the remaining part of the loop ran across the back side of the bag and held it away from the brake levers. The cam strap helped to absorb the road noise and I felt much better about the camera being in a dedicated camera bag. If this explanation makes no sense and you are interested in how it works, drop me a note and I can make the effort to post a pic.
The the nicest thing about this setup was it only took seconds to unclip the bag from the bike and pull the belt straps out to use it as a fanny pack so I did not have to walk around with a handlebar bag in my hand. I also left the cam strap on the bike and re-routed it through the front wheel as a quick theft deterrent.