On a long enough timeline, everything is a consumnable.

could you cut the closed cell foam pad to fit the sleeping pad sleeve?
or simply lay out the bag on top of the pad?[/QUOTE]

I use the Big Agnes Sleeping bags that has a Sleeping pad sleeve and only can use Air Sleeping pads 72x20x2 to 4in

If you are talking about the simple blue or green foamy pads yes you can. I always cut them down to size when I was climbing.

Whenever i need a new sleeping bad (very VERY seldom) I get a military one from an army surplus store. I like the foam pads for three main reasons. #1 . they do NOT lose air. #2 . They insulate from cold ground. #3 . They can be use as a bouyancy aid swimming or ferrying gear across water where there is no bridge. I often encounter the latter during my tours in Northern Ontario, Canada.

#4 . Compared to many inflatable pads, military surplus foam pads are VERY inexpensive and last for many, many years. my current one is about 30 years old.

Cheers

I have one of the same bags that you do. I cannot imagine how in the world a closed cell pad could not be cut to size and used without the first problem.

When I do use my "cut to size" Reflectix rectangle I put it the sleeve before I slide the Thermarest in. Has never been a problem. In fact, my Thermarest is not rectangular...it's a "mummy" shape.

Just my personal experience using the pieces of equipment discussed in this thread.

YMMV