I know the blind spot on the passenger side is dangerous. For me, the passenger headrest completely block the rear window. I can mitigate that by moving the seat forward but i often drive with my wife so she has to move the seat back thus block the rear window.
So I got this Clip-On mirror for only $10 from Amazon. It just clipped on to the rearview mirror. And now I could see what would be the entire blind spot on the ClipOn.
You should definitely try it.
You don't have to buy from amazon. a good auto zone would carry it.
Amazon.com: K Source RM011 18" Clip-on Wide Angle Rearview Mirror: Automotive