I had a cadillac that was originally purchased in Arizona. It had dark tint on the windows. 20%! Pretty dark. I loved it! Drove around in Wisconsin for a few years. I did get pulled over once for speeding, no front plate and dark tint. The cop wrote warnings, and said have a nice day. Never fixed it. I plan on tinting my Cuda once I rebuild my window bumpers. Probably not 20%, but more like 50%. Darker than legal, but not blacked out like a drug running car.
If you like the look, do it. Keeps the car cooler in summer, and looks good too. Why do you care what anyone else thinks? You are driving YOUR cool car. It can always be removed if you have to.