Chromophore, I had to stop for a minute & think about the size of your trees! OMB & I are growing little guys, SOG. We try to finish around 2' tall. The underlighting hits the sides of the bottom half of our plants, getting light to the lower buds. But you're kinda right about the undersides of leaves, but the photo cells still respond somewhat to the smaller amount of light they get from underneath, but we're mainly concerned with lighting the lower smaller buds to beef them up. This wouldn't help you at all. Your jungle is too tall for underlighting to reach them unless you used pole lamps!!!! I'm still playing the cartoon in my mind where you get lost in 'the jungle'! LOL!