Ive often wondered if you couldn't place the servo in front of the box and have the door SLIDE open.
Use a long control arm with a pushrod attached to the door. The door could slide on 2 little "L" shaped rails and then be opened and closed at will.
If you wanted ALOT of travel for the door, a little linkage inventiveness could do that.
Or I wonder about placing a control horn on the hatch and have the servo pull it down off of hinges. (like flaps)