I think you are OKish - the less noble metals in your example are also the biggest as I understand. Sheet metal - huge, least noble. Brass - more noble but way smaller than the sheet metal. And stainless inserts most noble but again smaller than brass brackets.

You will probably see some galvanic corrosion, on contact areas, especially because of the place you live.

Best you could do would be to paint it to seal it avoiding moisture getting to it.
In real world you probably will be fine for many years just covering it in wax