Lets move back forward on the fuselage a bit and look at the access panels on both sides under the cockpit:

In the first picture I am following the molded scribed lines with my trusty Dremel with the diamond wheel.

Cut only the straight lines as shown in the second photo.

Then I switched to a tiny end mill (.010") to freehand the curved corners of the panel doors in the third picture.

The fourth picture shows the opening after touching up the edges with some 100 grit sandpaper.