Re: Fc40 with Gropro without gimbal?
Since the GoPro is so much heavier, you might want to move the mount back under the center of gravity. Remove the front screw, loosen the rear screw, swing the camera mount around and mark where the new hole will go. Drill a small hole and put a small bolt through from the top - the bottom of the battery bay. This is the only tough part, getting that bolt through the hole.
Using the longer/wider landing gear helps, too.