Fit a concertina blind behind the driver’ head to cut down on the reflections in the windscreen and modify the wiring if necessary so the interior light in the front only comes on when the doors are open. Many van derived vehicles only need the front interior light switch to be set in a different positon.
Reflections in the screen can be a big a problem on buses even when there is a staircase behind the driver’s cab. In town driving this is not too big an issue but out in the country it certainly is. Often the 1st nearside interior light either has a lower wattage bulb or a blue one.