My current set up is 28 inch tree straps, 5 foot dynaglide whoopies with whoopie hooks. Weight is under 3 ounces total for both ends and I have used shorter tree straps and whoopies for a weight around 2 ounces total.
I usually hang from smaller trees and rarely need to use the whoopie to make up the distance.
I think I am going to experiment with short tree straps, 2 feet or so, a short section of tree strap extender on the straps and then short whoopie slings with whoopie hooks. Have not put it together yet to get a weight, but should be close to 2 ounces (the extenders and whoopie slings will be home made Dynaglide ones).