The sunshade will keep the interior of your vehicle significantly cooler. You still get the sun but not direct sunlight which will make the interior significantly hotter. This was the first mod that I did. It is still my wife's favorite.
I live in PA and bought 2 jeeps from Flemington Jeep in NJ. They give you a temp tag and once I received the registration I have to get it inspected in PA. If you are in NJ call them and negotiate with them on the phone.