I recently got a bunch of carbon fiber tubing for an electronics project, and noticed that the 1/4" diameter tubing is quite rigid stuff. Not quite rigid enough for using as a spreader bar on a bridge hammock, but it was pretty close. I would think that the .3150" or larger tube on This Page would easily handle the stress, and would be considerably lighter than aluminum.

For those of you that don't carry trekking poles, it might be the lightest option out there.

-Smalls