Hi
Dont worry, it gets mats on the top and the bottom, and over those, hydro turf. No reason to worry about the edge. And for Rust, i paint them with thick paint.
And the bolts and nuts are out of stainless steel, so no problem. The "Wings" are protected with primer,paint,glue,mat,hydro turf.... I thinks that should be enough to hold the rust back for some years.... The plate on the outside are made of stainless steel.