Dungeness prefer sandy bottoms. South end of the Sunshine Coast has quite a few. As you get past the Trail Islands, I've been told that you get into more Red Rock crabs due to the bottom changing to more rock. That being the case, there would probably be more box crabs in that area too. I don't think the doors on a standard dungeness trap will work well for box crabs though.
As for King Crab, you'll want to check the regs.... pretty sure you can't keep them (if you were to find them) anywhere on the South Coast.