In Alberta, you can random camp in Wilderness Parks and in Public Land Use Zones (PLUZ). Although I would avoid PLUZ as these are also open to off-road vehicles. The only rule is that you are at least 1km away from any road or Provincial Recreation Area (details here https://www.albertaparks.ca/albertap...untry-camping/
). I'm most familiar with Elbow Sheep and the Don Getty Wildland Parks west of Calgary. No permits or fees are required
In the National Parks, there are some areas where random camping is permitted. Banff for example allows random camping in the remote eastern sections of the park (as well as a few other areas in the north of the park). The eastern areas are typically best accessed from the Forestry Trunk Road (Alberta Highway 940), however these are gravel roads and some of the access roads can be rough. You still require a permit from Parks Canada to camp within the National Parks. Things are less well defined for Jasper, and I don't believe random camping is permitted in Yoho and Kootenay NP.
In BC I'm most familiar with Height of the Rockies Provincial Park, which does allow random camping, however access is either through Peter Lougheed Provincial Park in Alberta, or through long remote forestry roads on the BC side.
I'll point out that many of these areas can be extremely remote, with little to no facilities. Trails may not be regularly maintained with unbridged stream/river crossings. The only place I'm aware that you can drive up on a paved road (Alberta Highway 66 and Alberta Highway 40), park and hike into areas where random camping is permitted is Elbow Sheep Wildland PP. Gillean and Tony Dafern have written series of excellent trail guidebooks covering this area (http://kananaskistrails.com/books/