I like it, tho I don't know if I like it for $100.

Great out of the box thinking.

Cattail down would be my choice. Like the Natives
where I grew up used in their sleeping bags made of
cattail reeds.

I"m thinking a old style mattress for backpacking might
be cool too. You know, like the straw they used to use in
little house on the prairie.

Perhaps a vest would be easier to stuff and unstuff.

Maybe a quilt for backpacking or emergencies.