Well, you could tint the windows dark, but that brings on a whole set of problems. Laws vary but it's mostly illegal to tint the front side windows, illegal everywhere to tint the windshield, and other windows could be illegal to tint in some states too. Besides illegality, you'll look like a hoodlum driving a heavily tinted old Civic.
It may be possible to get a windshield with an anti-glare coating.
I think mainly you're stuck with manually blocking off the windows with shades or using a fan of some sort.