That's an awesome idea I wasn't even thinking along those lines. Done right I can even still have the center open.You don't want to mix anodes. Magnesium is not good in saltwater and can cause issues. I use Zinc on mine and like you do both Saltwater/freshwater.
As for the windshield, was thinking something pretty simple. Just an aluminum sheet that is bent to support the edge and then a cut out for the windshield (Plexiglass) and bolt on. Nothing extravagant and functional/cheap. Similar to this design, but just for one side.
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SHSU
You got the gears turning. I was digging around for aluminum channel and what not and decided it was more than I wanted to spend right now. But that is a definite possibility. Especially since I could go back and level my dashes I'm not a fan of the slant they have.
Thanks for the tip on the anodes and the windsheild ideas.