This weather sucks no matter what you do. Avoid overnight trip all together and for day-trips I'd go with minimal rests. Food in pocket and you don't have to do a "lunch stop". Yesterday has similar weather on Mt. Kelly so we didn't do any rest stop from car to summit. Only 1 tart on the summit and then ski all the way down in one push... To keep myself (relatively) dry what I use is a thin rain jacket with nothing but t-shirt inside. I keep most zippers open, and keep the pace a little slower than your normal pace. But of course if you go in a group then the pacing could be difficult unless you're the strongest.