Line up the plane in the general direction of your target before you go to the bombardier position. Calibrate your sight using a convenient landmark on the ground beneath your plane. When you exit calibration mode and get your green confirmation, then use the rudder trim keys to yaw your plane into alignment with your target as seen through the bombsight.
The better your lineup before you go to the bombsight, the less work you have to do hunched over the sight. And remember that, until HTC fixes the bomb bug, your sight figures in drag on the bombs, but the bombs don't actually have any drag, so you're going to be shooting long -- drop before your crosshairs are on your target; with some practice, you'll figure out what Tennessee windage to use.