Here's a muslin coat made up in a thin, drapey sweatshirt fleece. It's a very thin fleece but I think it does a good job as a muslin. I made the size 34 and I'll have to take it in a bit still. I did my standard petite adjustment above the bust.
Here it is with a random belt. I'll need to lower the pockets about two inches. The belt goes right over them. I'll probably shorten it by a couple of inches too. I feel like I'm wearing a bathrobe.