You've probably figured out a better method by now, but having 2 lines to grab from the dock, one on each of the pylons on one side of the boat, in addition to your 4 point crane harness, would give you 3 points of attachment. You're probably doing this already, but in case not. I am curious though about raising and lowering sails when launching form a crane. Do you do that on the water, or leave them on and then hook up to the crane? Seems like the jib in particular would be a real pain to try and raise in the water. I sail off of Evanston beach and there were a few times I got caught out in some very heavy stuff and thought of dropping the front sail or reefing, but realized it would be almost impossible to do in a big blow. I guess floating at the dock it might be manageable.