I'm not sure if anyone has tried a vacuum infusion on this site but peel ply also works well to make a nice inside surface.

The picture below show a kayak deck being infused. The last layer on the laminate before the vacuum bag is peel ply. After the part is infused the peel ply is is pulled off. Without the peel ply the wrinkles in the bag would be imprinted on the part (in this case deck) creating lots of ridges to sand down. The peel ply also creates a nice non skid surface for the cockpit area when you do the hull.