Mombasa Defender as a 7 oz tent, $26 at rei

Sounds good to me. I'm not sure I would call it a tent, though. Add a tarp and you've got yourself a tent (and a double walled one at that).

I've seen similar set-ups in North American backpacking. These things seem to be more of a mosquito netting for a tropical dwelling with ill-fitting doors/windows, or in a large bedoin-style tent if you've ever been out in the boonies in the Arabian desert, where there's worries about about saw scaled vipers.
I suppose if you found a suitable tarp to shield its considerable cross-section from winds it would work, especially if you can hang it to branches.

I was planning to string some line between a pair of trees, and connect the ring to that. This way I can camp in a clearing and still see the stars as I go to sleep.

I don't actually need to suspend the point if there is nothing suitable around, or if wind loads are high.

I used a Stansport Single Mosquito Net under my Gatewood Cape for several years and really liked it. The design is basically the same as the Mombasa Defender, but the price is even better ($15 to $20 shipped). Like the Mombasa Defender, it’s floorless, so I added a Polycryo Ground Cloth from Gossamer Gear. While not as a convenient as net tent with a zippered door, integrated floor, etc., you can’t beat the price.