Thanks, guys, but arrows have these nice hard steel tips which is good for pounding into the ground, tent poles not so much. I don't know enough about the strength characteristics of carbon shafts when being pounded on, but there is still that pointy steel tip thing that arrows have.
The author of the article I linked to writes, "For vertical supports [...] I favor ultralight, youth-sized, aluminum arrows like these with the flights and nocks removed. Made by Easton and others, they can be found online and in well-equipped sporting goods stores for as little as $2.50 per arrow. They weighs only about ½ oz each, or about the same as a typical aluminum tent stake, yet are strong enough to support the screen securely. The sharpened steel tips resist wear and are also great for penetrating hardened soils."
That be what I'm looking for.