What's the reason for the emphasis on weight? From reading the technical reports (from Makani), there were larger issues with the design unrelated to the weight.
As an example, Makani's Y-bridle design to attach the tether to the kite introduce stability issues during hover, and limited their control when the kite was aloft making circles, which in turn limited their power generation.
As an example, Makani's Y-bridle design to attach the tether to the kite introduce stability issues during hover, and limited their control when the kite was aloft making circles, which in turn limited their power generation.