I haven't ever heard of any objections to anybody painting legs, or any other bits, for that matter. It's just faces. I think you could black up all over your body with no objection, so long as your face is left your natural colour- or green, red, purple. Or whatever suits.

I've always thought it's a shame weren't a range of different colurs, instead of the pretty limited range of pale to dark we do have. Green, blue, red...