"Is it stretched horizontally to cover the opening to the upper poptop
area?"

Yes Keith. The front of the blanket has 4 snaps, and those snap across the
top of the opening where the pop top latches. Matter of fact I cut a slice
in the middle of the blanket there to straddle the male latch piece, and
that helps anchor that part of the blanket in the middle. About 5 snaps down
each side top so the blanket winds up being stretched across the entire
opening. I just tuck it in between the two mattress sections of the upper
bunk at the back of the opening. Real easy to unsnap to access stuff above,
luggage, etc. Most of what I'm going to need at night I just keep in a bag
in the front seat so I don't have to get "up there".

Richard Jones is the one who gave me the idea and basic plan. I do almost
all my camping alone so I don't have to accommodate volks in the upper bunk.
Combining that with the catalytic heater and the van gets cozy real fast.
Now heading for a propex to eliminate all the moisture inside .... RUST!

Wherever I have a snap on the blanket, I used iron-on patches so the snaps
don't tear loose from the fleece from continued use. Working real well so
far. At other times the blanket is just a blanket.

Hope that makes it clearer?

bob