for corrosion resistance. I have been told that Home Depot sells copper flashing for roofs. The marine stores are a huge rip-off when it comes to copper. They seem to be propagating a myth that thinner is better - it is not a factor for radio grounding. It is surface area that matters.

I replaced my thin corroded copper with 2-1/2 wide, about 1/16 inch thick copper that I bought at a surplus metal dealer that is no longer in business. I have not coated it. You could try Boeshield.