I live in Port Alberni which is right in your planned travel path (10min drive from Sproat Lake Prov Park). Some of the best shore diving on our island is in the Nanoose area which is is a 45min drive from the campsite. I'd be happy to show you around if you do end up in the area. Some of the major VI attractions are common occurance on these dives - wolf eels, giant pacific octopus, dogfish, sea lions, etc. This isn't the best of the best diving though.
I have to agree that your travel plans are a little ambitious for a week. Trying to hit all the attractions on all four compass points isn't realistic. Of all the places you list, Port Hardy is the best, but will consume much of your week. Tofino/long beach is a must see from a non-diving standpoint. Nanaimo has great wreck diving. Campbell River has great drift/wall diving. Victoria has reasonably good diving and places like Race Rocks are well worth a charter. If this is your first trip, and your camping, I'd personally stick to your plan (minus Port Hardy - which is a whole trip unto itself). Between Nanaimo and Campbell River you get the best of both wreck and natural sites. Tofino is just great camping.
Feel free to PM me if you have any questions. I've done 95% of my diving on VI and have literally dived all around the island.