No, the contaminates that encapsulate pressure treated so it does not rot will effect the lamination stability of fiberglass. It is also wet so it will have a low bond strength right from the get go.. Also PT is usually a CDX grade which is garbage more or less
If you don't want to use Marine grade, get ABX or ACX exterior ply. Good lumberyard will have it
I have used it for my deck years ago with good results but I would never cover it. As stated above under deck is not ideal situation for it. My deck is open and removable so I can inspect my wooden members inside my boat. All my wood is open to the air. It has been properly undercoated and painted. I also have installed a good quality outdoor carpet on it. It is also stored under a roof and does not get wet. Marine grade would work better for your circumstances.