oh man! I feel for you...I'm glad I never have to fly "thru the glass" style prompters.
My attitude is this: if Robert Starling can get away with a 7" LCD above the lens on Lopez Tonight, you client's can deal with it..
I'm sure you meant Rob Vuona on Lopez Tonight, and yes Tore and I both use a 7" prompter on that show and pretty much all shows for that matter.
Although there have been the odd times on a couple different shows where the director wants me closer to the talent at the wider end of the lens and the prompter on the top of the lens creates an eye line that is above the lens.
For that there is an 8" through the glass prompter that I use it's light and mostly made of plastic and aluminum.
Call "On Air Prompting" speak to Sharon . . . . (818) 406-2582
Otherwise, stick to the 7" above the lens, I fly mine almost touching the lens just above the iris ring.
Good luck and just say NO to that ridiculous 12" concoction you where flying