[Cory]

First off, you should not have trouble with breakers blowing. Your drivetrain should have the wheels slipping before you reach the stall current, so you'll never be pulling that much. Many teams have used 6 motor drives successfully in the past, and that's with all 6 running the entire match. If you have a total of 7 and are only driving 4 the majority of the time, you should be fine.

Second, the van door motor can be backdriven if you apply enough force to it, if I remember correctly.