Thanks everybody for your inputs!
In the meantime, I have also talked to Rosen. They say that they have not heard of problems with the suction cups leaving marks, but that the crew sunshades are meant for the rear or side windows rather than the windshield. I guess, because the pilot's vision would be impaired. But in my case I would mount them far up, just to get a bit more shade on sunny days, rather than protection from a low standing sun. The static film type sounds interesting and would maintain clear vision.
The Sedan's diagonal brace tubes measure 1" in diameter. Rosen's Maule sun visors come with 3/4" clamps, but a 1" version is available, too. I just sat in the plane and tried to imagine where this would all be mounted. If the copilot side visor is stowed back and up, the fuel gauge on that side might be hidden from the pilot's view. The visor is transparent all right, but considering the angle at which the pilot looks at it, reflections could be an issue. I will test this out with a piece of acrylic plastic. Another point: Originally, I had figured the bigger the better, meaning the larger the visor shields the better. But after sitting in the plane, I think the smaller version (approx. 8" of height) should be just fine and can probably be stowed away and out of sight better.
I look forward to hear about Joe's experiences with his installation. I wish my butler's Global Express needed new sunvisors, too, so I could inherit the old ones....
Matt