The better/steeper the berm/rut the more you can lean your upper body. On flat or cambered or slippery turns the bike must lean more with the upper body remaining more vertical. I tend to always lean the bike more than my upper body in almost all conditions, berm or not. The key in either case is sitting down properly, transitioning from brake to throttle, weighing the outside peg, pressure of the outside knee against tank/shroud, staying forward, keeping legs in against bike, turning upper body in direction you are turning, looking ahead, and throttle/clutch control. See recent thread on standing turning.