>>981096There are definitely ways to get 15 oz for a hammock, tarp, and suspension.
Hummingbird single hammock 5.2oz
Hummingbird suspension 2.3oz
Cuben Fiber Tarp 4.8oz
With that set up your just use your same sleeping pad and bag as you do in your tent.
Remember though, a hammock isn't about saving weight. It's about increasing comfort. If you are only trying to save weight, a tarp as a shelter is what you want. A hammock set up is really a tarp shelter that you have added a bed to.
Not everyone loves hammocks, but some people after using one will never sleep on the ground again.
It's pretty awesome to wake up in the morning in a hammock, and not have to crawl out of a tent on your hands and knees.