I do the same thing to protect tacky tape during layup. I also cut all pieces of glass and carbon out to size first. Check them for fit on the mold then number all from forward to aft in the upper aft corner. They are stacked on one end of the mold in the reverse order of the finished part. That way it's very hard to get mixed up and place something backwards or upside down.
My last boat was male mold using a caul plate to mold the outside skin. The caul plate is a flat plate of 3mm PVC sheet with a glossy finish. It's outside edges match the male mold edges when vacuumed against the hull side. Treated with mold release before layup.