I have vinyl instead of window tint on my quarter windows (as with all my other Mustangs), and it does cause a massive blind spot. All that you need to do is properly adjust your side mirrors and the problem is solved.
I had the side louvers on a 2005. I have to pull into parking spaces quite a bit and the view was seriously affected when backing up.
It is interesting to me that the original Shelbys had clear glass windows and no louvers. There are kits to convert the factory louvers (built in) on the early models to the glass windows. The new models have glass and many want louvers.
It seems everyone wants to change from factory no matter what the factory is.