When I got my llumar CTX done on all but the windshield (lightest tint they offer), I almost got the windshield done for the same exact reason of heat rejection. It’s the biggest window after all.
Instead I did a limo tint strip across the top of the windshield. It looks straight across from inside the car, and not that wide of a strip. I love it because unless it’s blaringly bright outside, I rarely wear sunglasses. When people get in the car they notice it right away and ask what’s with the tint, but the sight of it fades quickly.
About 2 months after avoiding the windshield tint, I had to replace the windshield, which was expensive since I opted for OEM glass, and losing that tint $$$ on the windshield would have made the sting even worse.
Still think about it from time to time, and avoid it because I know it’s only a matter of time before some debris tossed onto the windshield will make me replace the windshield again. I drive a road once a week full of trucks and there is always crap flying off of them.