um ... summiting with just a water bottle and power bar is definitely NOT safe. you should be prepared for a bivy in case of an emergency.
i'm interested in seeing what other people say, but here are a few of my thoughts: i'm not trying to tell you what to do ... but imho it would seriously suck to sleep at over 12,000 feet. much better to sleep at a lower elevation. if you want to acclimatize more at higher elevations, you could spend a day or two making non-summit trips up from an established "lower" high camp and back. and as for not wanting to carry a whole bunch of stuff on a 3,000/4,000-foot summit bid ... i would suggest more physical training.