I went to Topeak MTX Explorer Rack and Trunk systems. http://www.topeak.com . I have several trunks for it. No heel strike at all.
I started with a backpack but reaching for the handlebars with straps around/over my shoulders was a pain. I wouldn't trade the rack and trunk system for anything but when exploring I start at home and end at home or when commuting I start at home and end at work where I park my bike in my office so I never have to carry anything off my bike.