Do you guys keep your shoulders more in front or back of the body when pressing?
I have narrow shoulders and never could really feel the shoulders working... mostly traps when doing presses.
Since I keep my shoulders pushed back, upper back tense and started behind the neck presses - I can really feel them working... now I am eager on training them.
Are people with short clavicles in general more prone to overdeveloping their traps while working shoulders?
If you are only feeling the traps when pressing I would say that your delts are either 1) exhausted, or 2) the weight is too heavy.
Short clavicles don't automatically equate to bigger and stronger traps. It may appear that way (optical illusion) but you need to really concentrate on isolating the lateral heads of the delts... possibly with higher reps and lighter weights.
You will probably always feel something in the traps because you cannot totally eliminate them from your shoulder work. When you raise your arm to the side for a lateral raise, what is your trap doing?
Answer: It is flexing like a bicep right at the top and against the neck. People who are looking for larger traps might want to consider that...