I've come across this problem before working on a clients home.we constructed a box style gutter out of plywood. Cutting reliefs on the vertical pieces helps bend the shape easier and puts less stress on the box from springing back open. We lined the box with rubber roofing, and then We wrapped the box with coil stock. And painted the under side with a good exterior paint. It's has been 10+ years, I pass the home periodically , and it is still there. Staggering the verticals, from the seams of the bottoms, was enough to keep everything a single uniform shape. ...we attached it to the house with screws and neoprene washers. This particular home did not need gutter guards. But a decent solution is a system that uses a course sponge like material that water flows through, but other debris washes over. My biggest concern was that the ice would burst open the box. But it simply expands UP instead of laterally. I realize this post is 4 years old. But I feel that it's still a relevant problem with old, and natural homes. Maybe it can help someone else.