Hey Paul, that picture is SICK. By the seastate it looks like there's no more than 4-5 knots of wind yet you're on the wire. What point of sail are you one--looks like little mast rotation.
I still need to digitize my Huntington video--similar conditions and you'll see that I'm doing everything wrong. I guess I'm more of a luffer than choker. And I'm also a tack-blower and a capsizer. I'll move my blocks and give choking a try, though. The problem I have with choking, philosophically, is that it stalls the flow of air on the spinnaker more than a mild luff. Maybe I should reread Bethwaite.
Also, being at least 40lbs heavier than you may affect what works. I know I just can't trap upwind until it is at least 8 knots steadily; otherwise I'm better off hiking in and out. But maybe an adjustable height trap is that answer for me.