The better boating is further north than the southern gulf Islands. Desolation Sound and the Broughtons offer more, particularly the Broughtons which are never over flowing like Desolation and the southern Gulf Islands can be.
If you are open, consider living on Texada Island which allows you to keep a boat at the Texada Boat Club (kind of a boat club for those who only want to wear jeans). You have to be a resident of Texada to join. The location of the boat club gives you access to all kinds of wonderful boating. Most of the population is on the northern section of the island.