The clips are a safety feature.
There are air bags (they explosively deploy in a couple of nano seconds in a severe frontal or side crash) over
both front doors.
The visor would interfere with the airbag, shouid it deploy, and getting hit in the side of your head with the full
force of the air bag shoving the visor around on it's pivot point could be very dangerous.
So, MB makes it so it only flips up and down in front of the driver and passenger and cannot interfere with the
over the door air bags.
Imagine the lawsuit that might result from a severe head or neck injury caused by the sun visor hitting someone's
head when the over the door air bag deployed.
It's the same as the lateral airbags in the sides of the seat backs. MB wouldn't install suspension seats for about a
year while they figured out how the airbags have to deploy and then had to get it approved by the US crash safety
organizations.
Perhaps Hein, out in Hood River, OR could devise some sort of shade/visor that slips or clips over the top of the driver's
and passenger's window. Then, when the sun is beating down on the side of the van you could simply place the shade
on the window and roll the window up to secure the shade. It would not interfere with the over door air bag.
Hope this helps,
Roger