Scott,
When you come down to J dock, take a look at my arch on the Knot Now....I raised it about 6". I also have some 1" (I think) stainless tube that I might be able to use to Fab up a lighter than 8 lbs antenna mount for you. I need more partice TIG welding Stainless away. I used a piece of Aluminum to adapt my Raymarine base to the existing mount...I know that I should not use different metals, but it has not been a problem. YET