That shooting board trick is a lifesaver. For the glue-up stress, try taping the joint together with blue painter's tape first. It holds everything in perfect alignment so you can focus on getting your clamps placed right without the pieces sliding around. Did that on a recent maple box and it made the whole process way less frantic. Just peel the tape off once the glue grabs.
Yeah, the tape trick @evawells mentioned is a total game changer. I've found that using the really cheap, thin masking tape works even better for small stuff like box joints, since it tears off cleanly and doesn't leave much residue if you forget it for an hour. For bigger panels, I'll sometimes do a full dry run with tape instead of glue, just to practice my clamp placement without the panic. It saves so much time when you actually do the real glue-up. What kind of tape do you prefer for wider boards?