I believe that outside sun screens provide more protection from UV and heat than an inside shade. The inside ones may be "cooler" to install, and the electric ones are very nice. But where does all the heat go between the shade and the glass.
I use
Magne-Shade sun screens for the front and side windows. They are held on by very strong magnets. One magnet is attached to the inside by 3m tape, and the outside ones are in pockets sewn into the sun screen. As their web site states, it provides up to 90% protection against UV.
We just spent 10 days at NAS Corpus Christi. The front window had sun most of the day. I put up the front window Magne-shade screen and never had to close the front drapes (except when we went to bed) The puppy could still see out.
The Magne-Shade can be put up in less than a minute. It just clicks in place. It's my recommendation.
Oh! we had winds in excess of 30 mph and the shade stayed in place.