Thanks for that clarification Laurie. Here are some thought bubbles which might or might not help you in your decision-making! lol
Given that the dock is fixed, this would mean that sometime the water could be as much as five feet below the deck level. That would seem to suggest you would need some sort of hoist (and maybe a ladder so you could get down to the Island easily)
While your TI must feel like it weighs a ton, the actual weight you would need a hoist to handle is very much as the low end of commercial hoists. Similarly, if your dock walkway is 54" wide, you should be able to get the TI to the platform on a trolley OK (not the big one, but one of the smaller ones with the insert on top to spread the load).
I would imagine you could get the hoist to lift the TI up the 3 feet needed to clear the pylons before lowering it into the water. My guess is that the centre of gravity is just about spot on the front aka, which could make installation of a lifting strap easy, as the aka would be a strong enough lifting point (subject to a confirmation from Matt from Hobie hint hint

)
Building up a suitable davit would not be to tough a job for a handyman, and you could use an inexpensive boat trailer winch for single-handed raising and lowering. I would assume the TI goes on the hoist with amas folded, and mast raised...
Food for thought?
Tony