Just thought I'd share my method of single line suspension with everyone.
Photos attached probably explain it better.
But basically on a sinle line of 4mm Dyneema SK75 (will be chaning to 3mm or possibly 2.5mm SK78 soon) I use two Karabiners and a welded steel ring (SMC ring is probably better) to hang between two tree huggers.
At one end I tie an Evenk(Siberian) Hitch to the Karabiner on the Tree hugger
At the other I use the ring with 3 or four wraps of cord to tie an adjustable truckers hitch(release tension slide ring to position, re-tension)and secure with a simple slipped half hitch.
I don't tension the line to much as I need some slack to attach my hammock hanging karabiners.
The Karabiners for hanging the hammock are attached anywhere along the suspension line by forming a clove hitch around the karabiner (you could also use the wrap method like the ring, however the clove hitch will defintely not slip), I then simply clip the hammock in to these karabiners, Sag can be adjusted by removing the karabiner and re-hitching in place somewhere else.
I've attached images of a long and short hang set up with a fixed hammock sag.
I am currently investigating the use of Nacrabiners to replace the karabiners on the tree huggers and to just stick a couple of marlin spike hitches in the line and hang the hammock directly off them, although I cannot beat my current method for speed of hang.
Hope this is useful to some people, looking to hang from a single line.
"Coz I find strength in pain, and I will change my ways, I'll know my name as its called again"