So you would recheck your bags at the Air Canada desk after you leave the customs area. I see that your connection flight is also the last one of the day. If you miss the flight, it's AC's problem assuming your flights are on one ticket. Be insistent on meals, hotel and .....

What you can do is request seats as far forward as possible so you can get off the aircraft quickly at YVR, and walk fast/run to immigration. That along could save 10 minutes in immigration wait (seems the times for residents & non-residents are almost the same.)

Hang on to your LHR-YVR boarding passes so you don't have to pay the $5 AIF (and also the Fort St. John-YVR BPs to save C$15 on the way home).