I'm willing to try different approaches to figure out the right mix of easiest & cheapest for the solution to this whole tracking problem. HTC was kind enough to send me one of their new trackers to test out. The tracker only supports sending position data out through USB, so the Due isn't a good choice here. Instead, it may be something more like a raspberry pi. We'll see. As for the software stack, the tracker should be a great fit with the libsurvive software stack. From what I can tell, it will look a lot like a Vive controller, although of course it has a different USB device ID.
So, I now have two lighthouses and a tracker. But no controllers or HMD. I feel like I'm starting to build a Vive system piecemeal.
So, for now I'm focusing my efforts on getting this thing to work with libsurvive, as that seems to be the most promising path forward. I'm definitely not giving up on the microcontroller path long term, as I think it has a lot of promise, too. But a solution using this tracker would be much easier for others to duplicate in the near term.