I was thinking of using a compressor and inflating a piece of plastic or a cut and prepared inner tube from a wheelbarrow etc. inside the mast. This would squeze your laminate towards the wall of your mast, creating a very good sleeve. A layer of plastic and some precautions would need to be taken so you could get your sleeve out afterwards..
The problem is stopping the bag/tube you inflate from expanding and eventually bursting at the ends from the pressure. If it was relatively close to the ends, you could have worked from the other side. If you think about it and see what you can do, perhaps it's a strategy that will work. Got the idea from Phill and one of the methods he use to build tubes.