I was in the same position still have an inch thick thermarest must be over 20 years old relegated to going under camp stretcher mattress when camping, mid winter etc keeps you warm.
I bought a exped one about the same size for the wife so she doesn't feel left out.
Used to use closed cell foam previously to provide that insulation layer.
I went with an Exped https://www.bivouac.co.nz/gear/campi...ul-winter.html
Waited until they had a sale and bought a large (read wide) one for $200 delivered.
Light enough and comfortable.
Bookmarks