Here's what I do with my park boards.
I get a base bevel of 2 degrees. Then I round the edges between the bindings. Then I round the edges at the contact points.
I do this because I live in an icy area and the sharp edges from the bindings to the effective edge still give me a grip in the snow while the bevel keeps the edge off the rail. Once the edges start to get real beat up I get a 3 degree bevel and do the same thing all over again.