What we need is some clever kid to take an LCD screen the size of the display and put a rheostat or similar on it to adjust how much light it lets through.
On my Sprinter I tinted the upper third of the driver's side with really dark static cling style film. Never need to flip the visor over. Oh, wait... on the Sprinter you CAN'T flip the visor overThis should work good :
Amazon.com: Gila PB78 Privacy Residential Window Film, Black, 36-Inch by 6-1/2-Feet: Home Improvement
And I'm also thinking about having the roll down driver and passenger windows tinted professionally, but not the wing windows so that at night the mirrors will be easier to use effectively. In the Sprinter once I tinted the front sides at night a car with just driving lights on was barley detectable to my 61 year old eyes.
Now I know what to do with the excess self cling stuff from the Sync screen dimmer project......tint wings only as needed (off for the all night drive to and from FL, on while stealth camping the rest of the time. Probably will have to find a lighter tint than the one in the link to have it match the 28% though.