First, the higher nose trimming will not apply as much on you UltraCat, the rocker is probably very different and flatter. It is quite board specific.
The single pump thing was tryied with success several times in the longer lulls provided by windshadows on the other side of the bay, when entering the small Ile-Perrot yacht club bay. The wind was marginal there. My weight placement contributed more to the board trimming than the mast foot position.
In the prevalent stronger winds yesterday, the mast foot could have been a bit further to the front, in order to increase control. I reckon the nose could have been kept a bit lower at high speed, but not so much in order to clear the chop!
About the cold, I was happy to keep my helmet liner yesterday to stay warm. I also brought an old jacket to put over my wetsuit after the ride, but didn't need it. Next time, I will bring a wool hat to put on my head after the ride, I think it will do the trick for me.