Have you considered using Autodesk's 3D Studio Max instead of Chunky for your renders? I was looking at it a bit today, it's got a lot more power and a ton more customization settings. It's pretty advanced, I might try learning it though, I think it can run the renders quite a bit faster than Chunky can.
It's mainly for animation, but I have seen some still-renders people have done with it in MC, and they're pretty awesome.
3Ds max is infinitely more powerful and you can achieve movie level detail but it is as difficult to master as it is powerful
With several years experience working in the program I am still learning new tricks and better ways to do things