This is a follow-up. We now have a viable way to get to and from the water from the Duke Pt BC Ferries terminal. This opens up numerous car-free loop options from Tsawwassen. See the BC Marine Trails web map for details. You need a cart, of course and it is not exactly easy, but it could work for you. Darlene and I (with a little help) managed to bring our mighty 6.1 m Osprey Tandem kayak home this way from Newcastle I at the end of our 6 day trip from Salt Spring!
Many thank to brave SKABC members Kevin Hall and Jennifer Illsley-Hall for acting as trusting pioneers, based on sketchy details from someone (me) they had never even met!