I just spent the month of March fishing my way up the Island on my way home to AK and it was an interesting experience to say the least! Definitely lots of logging roads everywhere and active hauling going on right now. The 2011 Backroad Mapbook had limited info; some roads were even deactivated miles down from the main. The fold-out Coast Guard SAR maps are supposedly more accurate and detailed though I never purchased one...
Fishing was slow for me. I fished mainly the Cowichan, Gold, Eve, and Salmon rivers... low, cold, and clear water conditions... few fish in the rivers. Weather for camping, however, was stellar. I was also limited in where I could access certain runs/holes due to my recovery from knee surgery recently... but it was good therapy nonetheless.
If I went back, I'd take my pontoon, mtn. bike, some good tarps and plan to fish when it was raining. Good luck!