I improvised with some rope, climbing slings, and carabiners to suspend it between two trees. It probably rained 1.5" while we were there, but the billboard sign held up great and didn't let any water through. It wasn't windy, but the edges held up well under the tension the captured water created.
The only pouring that we experienced was a little white wine. After we were done with our trip, we just folded it up, and packed it away. Since it doesn't promote mold/mildew, the polyethylene material should be fine next spring when we need it again.