A thin plastic dropcloth isn't much shelter outside FL, esp where wind is an issue, and can give you a false sense of security. A woman I knew years ago used one as shelter in central OR (it was an accident that she even had it). Between the wind and the bushes, it got heavily ventilated. A tarp is worth the extra weight if you need it.

Two things tend to bite you in the butt: too cheap and too light.

Sue