Here is my bag setup at my camp. It has a 3'x3' section of metal roofing attached to the top if you look closely. It works awesome, it gets really windy in this field and it still has never blown over.

One of these days I'm going to move the middle support just a bit lower so that the bag can clear it and hang a bit more freely. I'm convinced that it is critical to lifespan of the bag to let it hang so that it can move and absorb a bit of the KE from impact.