I know we have all researched this a bunch so I wanted to add these pics to help others. I could not find pictures of anyone with anything bigger than a 798 mounted at the console. This ended up being very clean and I didn't have to put a single hole or scratch on anything to get this mounted.
5" muffler clamp with a 4" fernco fitting (black rubber for fitting together 2 pieces of PVC pipe) from Lowe's. All thread couplings, 2 bolts, 2 washers and some black paint I had in the garage. It is solid as a rock and the rubber (fernco) absorbs and vibrations. It fit the seastar helm perfectly AND is plenty sturdy.
That's cool! I mounted my Helix 7 off to the side though - seems your way blocks a little view, and I like to be able to see everything - gauge wise. Plus it sticks up over the steering wheel a little. But the benefit is no holes! I screwed my mount down through the dash.
It blocks the tach, old depth finder and speedo. The latter 2 of them I no longer need. I can still see the fuel, and trim. I will have the tach on the graph when I get my nmea 2000 cable. When you are sitting in the seat the screen is not blocked at all. I am always looking just over the top of the windshield.....so it does noes block anything.