Just fly under 400'. Won't that solve the issue? With the 94 degree lens, you'll get over 800' of coverage (width at 9:16 ratio). Since you're doing it for free, you don't need an exemption or license. Call the FAA. Get it from the horse's mouth. They're pretty easy to talk to.
But, you might as well file for a 333 exemption if you're going to be doing this stuff. It's free, not too difficult, but it does take several months for approval.
