I've never brought a cable along, but I've also never had trouble getting my bike close enough to a pole, even at campgrounds, and even with my "mini" u-lock.

Listen, if you REALLY don't want to carry a U-lock, then it's your bike to risk. Just don't post a picture of your cut lock and expect much sympathy from me. It just boggles my mind how folks will insist weight doesn't matter that much if you're hauling it on a bike, and suddenly, the area of security and the assurance you'll be able to make it home isn't worth an extra pound or so.