My gf and I just returned from a snowshoeing trip in Yosemite, and went with option #2. We had a lot of gear, and everything went into a single semi-rigid wheeled upright, and we had no problems. I just turn the snowshoes teeth/crampons towards each other and called it a day. I do the same with actual crampons. You could use a bit of duct tape to hold the shoes against one another if you wanted, but we didn't. After packing our boots, trekking poles, and other junk, everything was snug, with no movement. I definitely don't think a rocksolid hardshell is necessary, and in my experience, I find them more prone to breaking actually. I've had hardshells crack after a few trips due to their lack of flex. One drop on the corner of a hardshell, and there I was with a $50 voucher from Jetblue as compensation :/ You're probably taking trekking poles too right? Those alone make me hesitate with using a duffle...I can just see TSA man-handling leading to bent poles.