Looking forward to taking our kids to their first drive in movie while in the area for Thanksgiving. I see that the sound comes through the car speakers but is it possible to hear the movie outside of the car? Does the theater have speakers or do you need a portable radio? I am loving the thought of sitting in the back of the pickup cuddled up in blankets watching the movie. Our truck does not have a sliding back window. Any other tips for a great experience, like where to park for the best viewing, etc?