Long ages ago some vans were equipped with a fresnel lens which attaches to the rear window. It's like a 12 inch wide window that gives you a wide view of everything behind you. I bought a couple I found online from like the Philippines or Taiwan about 6 months ago. They were around $14 each. I originally installed one on each window. Since then I took one down. To install you just take it out of the envelope and place in on the glass. It just clings there. I love it. Helps visibility much! Wish I could help more with specifics but if you Google fresnel lens van, you should find plenty of help.