I've never understood the usefulness of short gaiters. Maybe in summer or spring, but not for winter, that is winter with snow - it's winter here in LA but it's 50 or so outside. I have tall ones I use with boots. I have used wire to tie mine on. String is useless in the long run.

If I was you, I would look at NEOS overshoes. They are designed to be worn with a shoe or boot, have real soles on them and some models have insulation. I'd buy the tall ones. I don't have them, but have read good reports on them from people who do and who use them in very cold weather.

Some overboots are designed to be worn over winter mountaineering boots and can only be used with crampons. Obviously those are not what you want, so don't get confused by the label.

www.overshoes.com