I guess you could do that, obviously you will be losing one summer break. But you may not have that many semester 2 courses available to do if you decide to push 2 semester 2 courses into the summer. You normally would not be able to do 2nd year courses.
You will also need a Distinction WAM to overload in your 2nd year.
You might have low contact hours, but not all courses may fit in your timetable. It's almost impossible to account for that. You may end up not being able to accelerate your degree by one semester.