Shooting for 3:1 Aspect Ratio

In the early stages of producing some corporate videos for a conference in NYC in a few months and was just told that they want content that is custom to the screen size. They have 3:1 aspect ratio screen and the resolution has to be 3240x1080. (12ft tall by 36 ft wide)

Originally i considered shooting normal 1080HD and framing it, but the client wants to have content that fits the whole screen. Any suggestions on how this can be done?

I haven't shot any interviews yet, but I was wondering if it was worth it to shoot wide and punch in, or if that would be too much of a degrade in quality. We shoot mostly on Canon DSLRs (7D etc). Has anyone ever shot for extremely wide ratios like this? Any tips or suggestions for shooting content for a screen that wide?

You could shoot with a 4k camera and vignette the frame in edit. The black bars won't matter in projection.
I'd find a way to make the client pay for the 4k camera. Sony has a few that are reasonable. The camera would be your reward for the hassle this will cause.

Yea, thats not a bad idea to shoot at a 4k Resolution because even cropping in would leave me plenty of resolution. I know FCPX can handle it, but Im not sure I have the space/storage needed to support 4k file sizes.