Flipping the camera upside down; how will this help my situation?

[constantballoon]

Currently have two cameras facing a busy street. One points down a backyard walkway and catches a glimpse of cars driving back and forth (you can see the top of trucks peaking over the top of our fence). Messing with the sensitivity does not seem to work and if I point the camera down further to cut off the top of th fence I will lose a great amount of important view. I have been reading that flipping the camera around has worked for some people but can someone explain to me how? Right now if the sensor is at the bottom of the camera, it is more in line with the walkway so I figured it should not be catching what is above the horizon (tops of trucks down the walkway). But If I were to flip the camera upside down and have the sensor on top of the camera, wouldn't it be more likely to catch the trucks even more as it is even higher now?

[VancouverBC]

Is there any chance you can power the camera(s) with AC power? Are the cameras under the eaves of a building and out of the weather? Then you can define zones in the field of view where motion is detected, Motion outside the zone does not trigger recording.