I am an ex front row rugby player when teaching in a C150/152 I have one arm over the back of the seats and my hips twisted through an angle. Just so I am not sitting on the students and they have a clear space to fly the aircraft. Door shutting is a game of doors, one side closes the other side pops open. The seat is always max travel back.
Tommy I can sit straight and my shoulders don't touch the student or the side of the aircraft and I don't have the seat at max travel. I will grant you the PA28 is similar but I comparison to the other two seater's it is roomy.