I know it is not in the Gulf Island but have a go at climbing up from Princess Louisa Inlet. Head up to the top of the rim to the small cabin and marvel at the fact that Mac had to carry everything up to the place. It's a good climb.
Then head over to Protection Island that protects Nanaimo which is a wonderful city. The island is a park and has a large variety of trails that you can walk all of them flat more to my liking. After a day of walking you can row over to the Dinghy Dock Pub which is acceptable only by water. A great place to visit for a cool one.
If you're at Nanaimo, don't over look the harbor walk way. It was completed in the last ten years or so and goes completely around the harbor. Protect your wallet from your wife as it has a number of excellent shops to buy things. What a way to hike!
Closer to home, Sidney Island just off from Sidney has a good anchorage and good trails to hike. Lots of wild life. And when you're tired you can head over to Sidney, one of my favorite cities and ports. Very friendly people.
Shameful advertising here but if you can, head over the American border to Roche Harbor, head just south and drop anchor in Garrison Bay, the British camp of the Pig War. Very smart those Brits in picking this place. A wonderful walk up Young Hill pass the British Cemetery (all died by accidents) still maintained by folks living in Victoria, BC. Great view at the top. This is my favorite hike.
I wish you well. Have fun. Tell us about it when you get back.