More than ten years ago, I purchased an Integral Designs SilShelter. Very quickly, I needed to add some mosquito net to it, so I sewed a skirt around the perimeter, and it is about 4-5 inches wide. Why that dimension? When it is stormy weather, I pitch the shelter sealed down to the ground, but when it is nice weather, I pitch it about 3 inches higher, and that ventilates it better, but it allows bugs unless that skirt is there. The net doesn't weigh much. I also added a net for the door/opening, and it is larger than one square yard.
Now I also have a GG SpinnShelter, and I am getting ready to do the same treatment to it.