Do you have the thin metal ring around the top of the windows for something like Rosen sunvisors? I've discovered the since Rosens are absolute crap, simply carrying a few small binder clips in my flight bag, I can rig up shades using pieces of paper and the clips fairly effectively.
And on a related note: Rosen can go straight to hell for using a rounded knob that can hardly be gripped properly but yet requiring 300+ft-lbs of torque to adequately make the visor stay in any position.