>  I suppose we could just insulate the
> square area from the edge of the upper bunk forward.

There was a thread on this a couple of weeks ago.
Someone used part of a quilt.  I bought a $7 fleece
throw and put snaps around.  Tried it out last
weekend and it works.  I got up, snapped it in
while my Carver furnace was heating up.  If really
cold, I'd snap it in the night before.  My idea
with the cheap fleece was to test, but I think
I'll just stick with it as sufficient.

Of course, I bump my head--but it is stretchy fleece.

                        Richard A Jones
                        Boulder, Colorado