Trouble is, even at 170 centimeters you're on the short end of backcountry skis. One option is to get a pair of Karhu Orion skis ($220; www.karhu.com), which are a so-called "short-wide" ski. They're a pretty soft ski, allowing good flex on rough terrain, and have metal edges for better turning and grip. And, they're available in 160-centimeter lengths.
Otherwise, your only choice is to abandon traditional skis altogether and go with something else. L.L. Bean's Boreal Skis ($250; www.llbean.com) are only 120 centimeters long but have all the trimmings of a real skiwith metal edges, an integrated climbing skin, and a built-in binding that fits over most cold-weather boots. They're meant for good skiers on rough terrain, where long skis will just get in the way. But they're also really not much more than a long snowshoechances are you'll find yourself walking on them, rather than really skiing.
So, my feeling is that the Orions are the sky for you. Short, but still a real ski, and designed for backcountry use.