This is a great design project. You're definitely going in a good direction and there is a lot of great feedback/advice here. I coach a competitive robotics team and we spend a LOT of time on designs that ultimately get scrapped, or have issues we fail to see in the beginning, so don't let that get you down. It can be tough to take the feedback sometimes, especially when it means going back to the drawing-board, but learning to be open to accepting this feedback will make you a much better engineer. Unlike art, engineering isn't personal. It goes beyond "design" and into the real world where performance, practicality, and in this case safety are all important things to thoroughly consider.
I'm also working on a design for a righting pole, with some similar concepts to yours. Easily deployable, stored under tramp, minimal complexity, lightweight. It's also cold where I am so I'm also unable to do any real tests until early June...
Some of my thoughts on your design:
-I agree with some of the other posts about the danger of the stainless wire-rope. I think you could substitute that for a synthetic rope. The same type of line that's used for your main halyard would be plenty strong, much lighter, and more easily cut in an emergency situation.
-If you're experiencing flex in the righting pole when you had only one guy-wire attachment point, perhaps you could add something to stiffen the pole. If you added a piece of flat-bar (on edge) on the sides of the pole experiencing the flex it would function like an I-beam and really stiffen the pole up. If you have access to aluminum welding this would be a really quick adjustment, and flat-bar is pretty inexpensive and readily available. You could also try filling the pole with some expanding foam or something to give it some rigidity.
-For quick release/adjustment of the dolphin striker attachment you could get a little cam-clamp bolt like on a bike seat. This would allow you to really easily adjust the placement of the attachment piece without tools and while on the water. You can salvage one from an old bike or make one from parts bought at mcmastercarr:
http://www.mcmaster.com/#cam-clamps/=10effyr- I like the idea of being able to keep the support guy-wires attached at all times. Less to do/think about when you're trying to right the boat. I would definitely try to keep that feature.
Keep at it. You have all winter to make it right! Looking forward to seeing how it turns out. I'll share my design too once I have time to get it from paper to real-life.