You'll only be able to clear customs there if that's your first stop in Canada. If you're planning to stop anywhere in the Gulf Islands before that, you'll need to clear at Bedwell Harbor, or maybe Sidney if you're going up the west side.
Watch the weather in the Strait. If the weather forecast is bad, many boats will not leave the marinas to cross the strait and stay in until it gets better. In other words, it may be tough to get a slip. It's happened to me twice.
Or, get a reservation if you can.
Another great option for provisioning is Ganges. Great little town with great little shops and restaurants. And, the well stocked Thrifty Supermarket will deliver to your boat!
Guaranteed your wife and family will love it!