Hemlocks can tolerate full shade and can be pruned to form a nice hedge. Consider cultivars. Monler may not get tall enough for the screen you want (tops out around ten feet) but has good screening foliage. Pendula gets a little larger.

Ever consider something closer to the house that is structural? a pergola or gazebo (overhead interest) would draw your attention away from the fence area and create a focal point. I find if you can create an area of interest that doesn't try to hide anything but is spectacular on its own, your eye is distracted by the horizontal plane and you never look "over the fence" :)

Though you gave a great description of the problem, is there any way you could post a picture from your house looking toward the area to disguise?

NatureBoy8888, did you ever solve this issue? I'm in the same position and would love to know what you did.