I use Rogue Amoeba's Loopback for this purpose: it is based on Soundflower, but with updated code and features. It works very well with Vuo.
I'm not sure what you mean by the "need to go to system preferences and choose soundflower every time", because I haven't use Soundflower in conjunction with Vuo and when using Loopback with Vuo, I certainly don't have to do that.
For a cube, I guess I would unfold it inside Vuo. But again, I believe the stitching, the alignment, the optical distortion correction, etc, would be the job for the video mapping solution.
