Definitely doable--even easier with Nexus. You will be closer to the front of the plane being in PE and hopefully no long lines even if you don't have Nexus.
I have gone from plane at international arrival through customs/immigration to domestic gate at YYZ in 20 minutes (with a bit of a puff) but I have Nexus and always in front cabin so use Nexus or Preferred security lines (whichever is faster). Always worth a shot. I think I have only ever missed once going on standby international to domestic (ie. not being able to get on a flight since it was full. Not: I don't fly YYZ-YXE)