I don't find myself close enough to the enemies to worry about position changes, I'm normally far ahead. For me it is just a matter of trying to time the shields for the right times, making sure that the rockets don't wipe me out when they do get sight of me. Maybe that's the idea that you should try out, the shield timing could be the difference between getting a good lead, or being stuck with the group. Remember to use your mines as well, they can be quite useful.