Thoughts on managing overnight risk for Asian equity positions?

Still getting my feet wet with Asian markets, mostly focused on $NIKKEI and $HSI for now. I'm finding it tough to size positions properly when holding overnight, given how quickly things can move before I even get a chance to react at open. My stop-loss is often blown out before I can even do anything. How do you guys manage that risk? Do you just size down aggressively or is there some other trick I'm missing?