You're welcome SB.
I'm thinking more in terms of the Golite Lair 2 (plus 2 Golite groundsheets) which comes in at a total of 450g, whereas the Hilleberg Nallo absolute minimum is 1900g. OK I know I'll need a couple of the lightweight groundsheets which increases it by 90g each.
I like the idea of using this with my gore-tex bivvy, but that adds another 800g as opposed to the 90g groundsheet. Now I go back a while, to when a two man tent was made of canvas with wooden poles (imagine what that weighs wet), so any backpacking was done with a (sort of) waterproof sheet, which we then called a 'bivvy'. We'd stretch this wherever we could, so the idea of sleeping out with just a waterproof top and a sleeping bag isn't too alien to me. Whether I'll feel the same way now ... ? But I'll give it a shot and if I get fed up I'll abandon the trip and head for the nearest pub.
I too have been looking at the Hennessy hammock, but like you have been a bit worried about using it outside woodland, and some of the places I expect to be I know there won't be many trees around.
Cheers, S.