If you're handy with resin, you could take a relief of each of the hatches you wish to open with something as simple as plasticine and then just pour in a few drops of resin into the mold to create a replica. The inside face can be replicated with thin plastic card. You would then file the hatch on the model flat and drill out the opening. Alternatively, you could use a pin vise to drill around the hatch to remove it, but then you would have to rebuild the area around the cut-out. I think the first method would be the easiest. Howard