I have decided for copper for the rims. Finally.
White will only be used for the head, the weapons, the markings and the imperial eagle above the helmet. The white rims did work to some extent, but I think I will have to try it another time!
Thanks for all the input and suggestions. Tomorrow I hope to get all the copper areas finished to 90 percent and then glue most parts and start on some serious weathering over the weekend!