Nothing will be sticking out of the hole, it's just so the camera can see out the side, without mounting it on the side of the rocket. I could 3D print a cover for the hole when I'm not flying with the camera.Will anything be sticking out of the hole?
Can it be closed again permanently?
\If you're worried about it, put some kind of feed-through or grommet around it so it seals the hole. A 1" hole can be huge or small, depending on the diameter of the payload tube. With a 2.6" tube, it's an "iffy"... it wouldn't hurt to seal it.