You should be able to get the servo in and out, even after the halves are glued together.

You can fuel proof the fire wall by thinning out some epoxy and coating all the exposed wood. You can cheat by using CA, but in my opinion it does not last as long, thinned epoxy is probably the best.

The CA will wick into the hinges on its own, and 4 drops on each side would be a minimum.

A thick sewing pin might work, the goal is to keep enough gap between the two parts to allow the proper range of motion with out binding.