Casinos are also a good bet for dry camping (to me, boondocking means being in the "boondocks"; "dry camping" is what we do in a Walmart parking lot or, in the U.S., most Forest Service campgrounds). The casino in Prince George always had a dozen or more motorhomes and big fifth wheel trailers camped in the outer rows of its parking lot last summer.
We also saw some Canadian Tire stores that allowed parking lot camping. And the entire Walmart-Safeway mall in Hinton, Alberta (just outside Jasper NP) allows camping in its parking lot and has great free WiFi inside the mall.
Also, check out city parks in the small towns in BC and Alberta. The lakeside park in Burns Lake, BC, on the Yellowhead Highway was free and had potable water and a free dump two blocks away. Milk River and Hythe, Alberta, had very nice, inexpensive city park campgrounds with electricity and water and a sanidump or even full-hookups for slightly more cost.
Also, check here:
Free campsites, then click on BC and Alberta.