The Skerry is so light, it wouldn't take much of a sling to hoist it.  I'd be inclined to go ahead and use the spacered inwales.  I'd have 4 web loops to slip through the inwales and just secure with "luggage tag" loops and then have a ring made up with 4 legs of line or web that lets you hook the 4 "luggage tags" to the club's hoist hook (I'm assuming they have a jib crane type hoist that lets you pick up the boat, swing it over the water and lower it).  Adjust the lengths of the legs to get everything pretty even and then color code everything so you know where they go.

If the inwale is glued and screwed to the spacers, there should be plenty of strength margin.  Just don't hop in the boat while hoisting it.

If you are uncertain about that, my next choice would be a pair of slings that go right under the boat and then up to a 2x4 spreader bar.  The bar would go fore/aft above the boat to keep the slings apart, and another short web would go from the bar to the hoist hook.  If you are smart about it, you could have the webs under the boat with loops sewn on each end and a snap shackle or carabiner on each so once the boat is down, you unsnap the two ends and pull them from under the boat so the bar and webs all stay on the hoist hook.  Pull up the hoist some and swing it back after splash so you can disconnect easily.