When I'm in Prince Rupert waiting for the ferry I usually park at the Olive Lake Provincial Park about 5 miles east of PR. I've spent 3 consecutive days there without being bothered by the RCMP. You do have to put up with a lot of dog walkers who are exercising their dogs. Also the toilets are very busy all day and night. But, it's free and comfortable for us.
In Prince George I've boon-docked at Walmart and Costco. No problems at either spot. I prefer Costco as the parking lot is very level compared to Walmart's.
