Why not just tint the whole windshield? 1% would be best.
Now, in all seriousness.... WHY? That 3 or 4 inch tint band at the top of the windshield won't do much to block additional light from entering the cab. Sounds like you picked the wrong interior color if you're so concerned about the interior brightness of the vehicle.
Furthermore, I don't know what state you're in, but 5% on the front windows is illegal in most states. I'm not saying "OMG! Don't do it!". It's your truck, your money and your tickets you risk getting, not I. As such, for all I care, you can paint ALL the windows with black paint.
You also have to take into consideration what kind of film you're going to have applied, as the percentages vary from manufacturer to manufacturer. What one manufacturer calls 15%, it may really be 20%, etc. . The crap from Luminarc and Solargard is just that... crap. The best (and closest) percentage matches that I've found have been with 3M film. Furthermore, due to the composition of the film, it will allow you to see out much better than comparable tint percentages from other manufacturers, while keeping prying eyes out equally if not better than similar percentages from other manufacturers. Expect to pay more for the 3M stuff.
Then of course, you'll have to find a tint shop that will apply 5% on the front door windows. Unless you have a buddy that will do it, it's very unlikely that a shop will apply such percentages on the front door windows, if you were to walk in off the street.
Either way. Good luck. My ultimate suggestion, don't tint the top of your windshield.