according to a color wheel and my old lady who is also an artist and knows all about color theory even confirms that orange is the opposite color of sky blue and the most contrasting. Black also shows up very well.
I also know when I had a set of prop guards were two were painted safety orange I could see them really well even from far away. Its always make me want to some day do a hydro dipped tiger striped one with orange and black. Or maybe a black and orange flame pattern would show up good and still look great as well.