Finally made the decision of fire and tested some colour variations, including a dark colour scheme as an experiment. I think I'll be going with #4, of course re-adding the gradient waist and glowing lines on her skin.
I'll update the thread title to reflect this, but a name has also been chosen for this champion, with some thanks to a friend who knows much more Chinese than I do. Zhū Huáng (朱凰) - Zhū (朱) meaning cinnabar, vermillion, bright red; Huáng (凰) meaning phoenix. If anybody notices a glaring mistake in that, please let me know!