Dean,
Mine were about 6" from the skylights as well. The problem is this... they insulate too well. When you close them, the air in between the shades and the window cools down, and it cools down on the window side first. That causes water to condense on the actual glass itself. Then, as nightfall progresses, that water freezes. When you wake up, you'll do one of 2 things... you'll either open the shades, or you'll leave them closed. If you open them, the warm air from your room hits the glass, melts the ice, and the water drips down the lower side of the box, and across your ceiling. If you leave the blinds closed, the sun eventually hits the skylight, melts the ice, and it drips on the shades. Trust me on this one, I spent some cash buying these things, and have opened and closed them during the process to learn what was going on. Now, if you only use them when it is "cool" outside, and not like 15 degrees out, they work fine. Its when the temperature difference is great enough that the problem arises. Also, I don't keep my home very humid in the winter, I can't with the insert going. If anything, its on the dry side. I do have cathedral ceilings though, which may be different from your house. My main ceiling is 35' high, 2 others are 29' high, and one is about 24' high. There are fans up there, so the air is pretty well circulated, but still, its something to consider... my situation may be different from yours.
Let me know if you have any other questions, no problem giving my experiences here...
-- Mike