From my experience, that would be a lot to do, unless you can study at work. When I used to teach at the college level, the assumption was that students needed to work 3 hours outside of class for every 1 hour in class. Do the math! What kinds of grades are you aiming for? I always went for all A's (and only made 3 B's in college), and I found 18 hours in itself plus being active in groups on campus was taxing.