It depends on the trip as to whether I'm in a tent, hammock or bivi and tarp.
For winter trips in Kosci, I use:
tarptent which is a skinny tube and doesn't take up much room
Exped UL mat
Thermals and longjohns
Two weeks ago I slept out with this setup:
When winter hammocking:
3x3m tarp with the "doors" closed (makes all the difference)
top and underquilt
I put a big 50L drybag inside my pack, then all the puffy gear except the tarp and tent goes straight into that. By pressing out all the air and sealing it, the insulation only takes up about 15 or 20 litres of space in the pack.
A huge amount of room gets lost by packing things in their own drybags or compression sacks.
I use the same exped mat as you, but I fold it into a flat square and it goes in the bottom of the drybag, this way there are no dead spaces between gear.
How do you find sleeping in the loft jacket Wentworth? I'm contemplating something similar, curious how you find it.