I'm okay with us losing the game on the basis of kicking (I hope the Reds are). Campbell, Daugunu, Stewart and O'Connor are all quality goal kickers - they should all be kicking around 70%. I don't think there will be too much difference between any of them. But keep in mind Campbell didn't exactly have the easiest kicks last weekend.
I'd tend to keep O'Connnor from regularly kicking considering he's still adapting to playing Flyhalf, but as a replacement or for the odd kick let him rip. As for Stewart, if/when we get some other options at 12 I'd tend to keep him focusing on his game there. Same for Lucas keep the pressure off him while he adapts to Super Rugby. That leaves Hegarty, Campbell and Daugunu, I'm happy for any of them to kick goals it'd probably be in a similar order, maybe Daugunu is above Campbell, but either way Campbell and Daugunu are a step down from Hegarty.
It's just too bad about Tuttle...