I couldn't care less about whether Law actually is yellow or gold. I just found your insistence rather amusing, lol.
That aside, using solely the colour wheel theory, I think the missing colours go to Carrot, Ace and Sabo.
Carrot's lime as stated
Ace is vermillion in between Nami and Luffy
Sabo is violet in between Sanji and Robin.
I think Oda used the wheel for the 11 straw hats and Luffy's two brothers. And if you check out the colours from the poll, they match up perfectly.