I was thinking to make poncholiner.

Poncholiner is like shirt with hood. Quilt or over quilt to add warmth. Maybe it can be bivybag?

Any ideas?

Timo: Within the USA there is a big culture of poncho liners, including Brigade Quartermaster edge zipper kits to turn them into lightweight sleeping bags etc. Kifaru makes one, called a 'Woobie'considerably warmer than the root of the USA poncho liner culture-US Army surplus poncho liners. Living as you do North of 60, I think some of the other Kifaru ideas, such as wearable sleeping bags, are more useful for me in the Canadian North, where even in the summertime our lows are in the +5C to -5C range!