I knocked up a pair of these roughly based on my drawings and warbonnetguy's recommendation of opening the v-cleat side.
http://l2i.org/hammock_vcleat.jpg
Made out of 3mm (.12") extruded aluminium (aluminum), the pair's combined weight is 18g (0.6oz), but you'd only need one if you wanted to save weight. They seemed strong enough, but I'd much rather repeat the exercise in 5mm stock next time for a bit more safety margin.
The additional strength added by closing the loop seems to have made a lot of difference and the cleats survived a few bounces without any sign of damage.
Actually, on the first bounce, I ended up sprawled on the ground. I had made the profile with a nice sharp edge, like on a knife and that nice sharp edge sliced straight through the paracord that I was using. I quickly rounded all the edges with some emery cloth and ended up with what you see above. It's not pretty, but it still bites and grips well.