I don't use pack covers because I've snagged every one of them and tore them off the pack or ripped up the tie/cinch straps on them trying to avoid that

I put my tent/tarp, and my sleeping bag, inside heavy duty plastic bags inside my pack. I've never had a pack soak through either, but I'm also not in the PNW. I've been there, and was amazed at how wet it was, so I can see why you'd need some specialized gear there.