The boat manufacturer had reco'd spreaders forward and max pre-bend as my default setting, which I thought would de-power me too much. Your comment makes me think that with max pre-bend it would be better for these conditions.
Spreaders forwards and max(although limited) prebend will stiffen the mast allowing you to "power up" for most conditions. Moving the spreaders back will allow you more potential prebend dependent on diamond tension. It also looks like you may have overdone the mast rotation. That could explain why the main would appear to luff. Try not to have the rotation lever pointing further aft than the end of the rear beam.
In strong/gusty conditions DON'T PINCH, unless you have to for survival reasons. When pinching, the boat will stall in the water and you will go sideways. If you sail a few degrees lower with the boat driving through the waves, the ride will be much smoother and considerably faster. Control the gusts on the main but steer straight.
Cheshirecatman