Charlie, we've also had some luck using the very light shade cloth available for our greenhouses - this comes up to very large sizes and the low density is not that heavy if you have supports created. I also like the finer weave, which really does block most things rather than just tangling them. I don't think that a light shade cloth (30%) is going to have a detrimental effect for a few weeks of use. They come with grommets every 2' and sewn edges. We just reuse old covers from our hoop houses and I'll bet if you kept your eyes open you could get some large bits cheap the next time a grower gets new shade cloth or a greenhouse biz closes. You could request a sample and see what you think. One source: http://www.atlasgreenhouse.com/equipment.html