With the exception of airflow effects, the position of the static port in relation to a barometric altimeter is irrelevant - it is the pressure affecting the capsule in the altimeter that determines the reading.
Consider, for example, a barometric altimeter positioned at the top of the CN Tower, connected to a 1000ft lenth of tubing hung over the edge of the balcony . What would be indicated on the altimeter?
The answer, of course, is the vertical position of the altimeter, not the open end of the tubing 1000ft below. The pressure of the air inside the tubing will decrease with altitude in exactly the same way as the air surrounding it and removing the tubing from the back of the altimeter case will make no difference at all to the reading.