So, I ended up going to the Best Buy on Route 9 in Manalapan, NJ. As I mentioned, select Best Buy stores held an outdoor movie screening of Harry Potter and the Deathly Hallows Part 2 on Thanksgiving Night.
I must say, I was HIGHLY impressed! My original guess was that they were going to pull out a Sima Inflatable screen (since they sell those). Boy, was I wrong. They had a HUGE mobile LCD screen, mounted on a tractor trailer. This was by far the most expensive outdoor movie set up I've ever seen. I'm thinking the screen was somewhere between 30 and 40 feet wide. And, it was competing with direct light from the parking lot lights. NO WAY could any of my set ups handled this.
The audio was ok, not great, just ok. It was loud enough, and if people weren't talking in line, I would have had no problem hearing the movie. The audio consisted of two speakers on stands on the very back end of the trailer. You can probably make out the speakers in a few of the pictures below.
Speaking of pictures, here are a bunch (I was also testing my new camera in low light):
Below: before the movie started:
Below: movie started
Below: different angle
Below: view of screen and Best Buy
Below: shot from behind the waiting line
Below: side view of screen
Below: closer view showing the back of the screen and support structure
Below: this is what the truck looked like after the screen had been lowered back down into the trailer