I fully tinted my 2003 Jaguar S-Type... 5% (Limo) rear and 25% front sides and only got ONE ticket in 2.5 years by tinting the front windshield 50% which is actually quite noticable and cool looking... guess the cops were too busy with LA crime to mess with me...
I noticed a big difference especially when getting into the car after being parked in the sun for hours.
Every 2 or so years they come out with a better tint that helps with the heat transfer.... so if you don't wanna get caught... I'd say even the minimal tint which is almost undetectable would help....
Cost on front windscreens is high... since it's not legal, and there's apparently a much higher chance of damaging the glass... I was charged $150.00 to do my front, and $80 to do the rest of the car (rear window looked harder to do, but who knows the price game)
Thanks for the idea though... I noticed on 97 degree days like we have today... after being in the sun for an hour, I could barely touch the steering wheel.. it was buring me..... then 2 miles down the road, my feet were cooking from the footboxes not being insulated.... get to ad that tomorrow... looking forward to NOT melting my Crock plastic shoes anymore!!!
Other than that, maybe a $7.00 reflectorised windshield folding cover thinngy would help....