You could use yarn(dont tie this on tightly.) to tie around the plants and then duct tape to secure both ends of the yarn to the buckets. I hope thats a clear enuff explanation. I had seen someone use party ribbons instead of yarn...it was quite colorful.

And actually ribbons, all jokes aside, are good for LSTing. Because they are wider even then yarn, which spreads the tension over a greater area, making it less likely for it to bite into the stem.
I unfortunately dont have the thread bookmarked, i dont even remember what forum i saw the picts on.
MJ is very resilient and it bends easily. But if you tie it down so far that its at the limits of its flexibility and then it gets bumped with alot of force, then it might break. If youre worried about it, dont overbend them, leave some slack. I wouldnt think they would snap from the wind.
Hope that helps