I've posted my hammock sandwich technique in the bottom insulation forum. It works beautifully and all you usually need is a spare old hammock, the insulation of your choice, and possibly 1 or 2 small lengths of chain.
Put the old hammock under the newer hammock then sandwich any insulation of your choice between the two.
As a full time hanger and being about 170kg I go through hammocks every 6 months or so, as they start to stretch out of shape. I am never short of matching spares.