After spending some time looking at different real-world aircraft with similar high-wing two engine designs to my Twinstar I have settled on a combination of US Coast Guard and Australian Customs.  I like these designs as they use lots of white (which save me having to do a lot of detailed painting) and should provide highly visible orientation when looking at it from the ground.  It should also give a good scale effect – in other words from a distance look just like the real thing.

I am basing my design on the Aust Customs Dash 8