I always caught the ferry over. Never had more than 2 weeks off work so didn't want to get stuck on island with bad weather in the Hecate. It can easily blow 25-30kn for a week straight up there even in the summer. I wouldn't worry about running across if the weather is good. In bad weather it can be one of the worst places on the coast, but it's been crossed by kayak, row boat and at least one 12ft lund with a 9.9 that I know of. Just pick your days.
I haven't stopped for fuel in Hartley Bay. I've always packed enough fuel when I've been in the area. Buddy in Kitimat has warned me about the fuel dock there though.